Monday, July 25, 2011

The title, of course, evokes one of the all time notorious science fiction stories - from geek perspective perhaps the notorious SF story: 'The Cold Equations.' I have been in the bashing school regarding that story, on the grounds that the most basic safe operation procedures should have prevented it, and more broadly because it is anvilicious. (No, I won't link the Evil Website. If you want the link, google it.)

A fair literary response is that the anviliciousness is the point - people may argue about the story, but if you've read it you remember it.

This post is not about the story itself, but about those cold equations, specifically as they relate to reaching Earth orbit. And for that purpose, the grump about the story is, if anything, understated. Realistically, the spacecraft in the story should not have had anywhere a stowaway could hide in the first place. It would be like stowing away in a Formula I racing car.

The cold equations we are specifically interested in are handily available at the Atomic Rockets site. Orbital velocity in low orbit is about 7.8 km/s. Add the potential energy from being about 300 km up, and the kinetic energy needed to reach low orbit corresponds to about 8.2 km/s.

There are also some unavoidable losses from air friction and gravity. In a vertical launch, 1 g of your initial thrust just goes to hovering, adding nothing to your speed. A horizontal launch allows aerodynamic lift to do that work, but means more aerodynamic drag.

If your launch site is at low latitude you also get up a few hundred meters/second of rotational velocity as a freebie.

These variables are, well, variable, depending on vehicle configuration and launch site. But taken together, expect to burn some 9-10 km/s in delta v to reach orbit.

Now we can play with some (very crude!) virtual orbiters. Captain Obvious reminds you that these numbers are not remotely authoritative: for one thing, I routinely round off numbers to 2-3 significant figures.

The highest performance propellant mix that we can really count on is H2-O2, which is good for an Isp in the range of 420-455 seconds, corresponding to an effective exhaust velocity around 4.2-4.5 km/s. Performance in atmosphere is lower. Delicately ignore that for the moment.

Cutting to the chase - and in the best case - getting to orbit calls for a mission delta v equal to at least twice the drive's exhaust velocity. For an SSTO that corresponds to a mass ratio of e^2, or 7.39, or an 86 percent propellant fraction.

To simplistically model more conservative assumptions, again set effective exhaust velocity at 4.5 km/s (still ignoring atmosphere!), while equivalent mission delta v is 10 km/s. In that case the mass ratio rises to 9.23, for an 89 percent propellant fraction.

This is the truly cold equation, because it puts convenient space flight pretty much out of the running. In the ideal case, if your launch mass is 1000 tons, 860 tons of that will be propellants, with the remaining 140 tons for the tankage, thrust structure, engines, minor items such as the guidance package, and (oh yes) a payload. With more conservative assumptions you have 890 tons of propellants and 110 tons for everything else.

These proportions are not, in themselves, impossible. The first and second stages of the Saturn V had dry weights of less than 8 percent and 6 percent of loaded weight respectively. But the first stage used denser kerosene and LOX with much lower performance, while the second stage used H2-O2 but had initial acceleration of only 1.04 g in near-vacuum, and at sea level would have been unable to lift itself off the pad.

For the current state of the art, the dry weight of the SpaceX Falcon 9 first stage is about 7 percent of load weight, but it also uses kerosene and LOX. A tank for H2-O2 would have to be much bulkier - about 3 times the volume capacity - and thus much heavier.

The bottom line is that an expendable SSTO might be viable, but offers no advantage over two-stage expendables. Any saving in operational simplicity (no staging separation or second stage startup) would be have to be balanced against the extremely narrow margins of the design.

Note that both Americans and Russians used 'one and a half stage' designs for their experimental ICBM models, Atlas and R-7 Semyorka - both of which went on to very successful careers as space boosters. Their designs allowed all main engines to be started on the launch pad. But later developments added a true second stage, and modern generation boosters have at least two stages, often with boosters strapped to the first stage.

The Shuttle was (we must now say was!) essentially a 'one and a half stage' orbiter, with recovery of the solid boosters, engines, and payload bay, but expendable main propellant tank.

Getting to a recoverable SSTO rocket would require a tech revolution - either dramatically stronger materials, or dramatically more powerful propellants. Neither is impossible. But likewise, neither is foreseeably in the cards.

An airbreather ascent, as proposed for Skylon, does not call for quite so big a tech revolution, but still requires a couple of very big pieces of undemonstrated technology - jet engines operating up to Mach 5+, then efficiently shifting into rocket mode, and a huge, lightweight airframe capable of handling the heat loads.

Skylon is awesomely cool, but just as awesomely demanding. I can't quite rule it out, but I wouldn't want to rely on it.

Two stages makes it all a lot easier, which is why two-stage boosters are now typical. A fully reusable TSTO vehicle is almost certainly possible. Whether it would be viable - that is to say, competitive with modern generation expendables - is a much iffier question.

And because I've made you wait so long even for this much, I will take up recoverable TSTO, and its alternatives, in an upcoming post.

Related Post: 'The Cold Equations' came up here previously, in the comment thread of a post about what constitutes hard SF.

The image of the X-37 unmanned spaceplane comes from the Christian Science Monitor (which in spite of its name and affiliation has had a good reputation over the years).

199 comments:

I'm not really sure what this post's discussion should be about, so I'll speak about technological progress. Just today I've found the following piece of news.

"University of Minnesota engineering researchers in the College of Science and Engineering have recently discovered a new alloy material that converts heat directly into electricity. This revolutionary energy conversion method is in the early stages of development, but it could have wide-sweeping impact on creating environmentally friendly electricity from waste heat sources."

And by doing so they've removed a need to attach kilometers long radiators to spaceships.At least in theory...To theoretical spaceships...Seems good enough for me!Laserstars just become a bit more plausible.

***

And speaking about progress and trains (again). Only recently we too have developed bilevel rail cars!Here it is. And here's the old one, from the beginning of 20th century.

It won't remove the need for radiators because that's not thermodynamically possible. From googling, the device works like a thermocouple and needs a temperature gradient to work. Ground-based applications are usually surrounded by comparatively cold air or water. It'd still work in space, like thermocouples (we use them with RTGs), but it doesn't change anything with regards to radiators.

Would carbon nanotubes provide those dramatically stronger materials? I know they are often over used in fiction, but they seem to be the closest to being perfected for production right now. And could you make a poor mans Skylon with a highflying spy plane and a rocket?

Maybe using a mixed approch; using a maglev or rocket sled to boost a vehicle to Mach 1-2, before its air-breathing engines loft it up to the edge of operability, then either transistion those engines to pure rocket or simply shut them down and start up actual rocket engines (I'd use hybrid rockets, myself); then it glides down to land at its original take-off point.

I read recently that a rocket booster and a Boing 747 cost about the same, but you throw away the rocket after one use so the cost of rocketry is huge compared to air travel. While that may be an economic argument for reusability, the engineering hurtles are still sky high.

Yes, as I've mentioned before, the dirty little secret of the Orion nuclear pulse rocket is that it is best used to boost payload into orbit. Which of course maximizes the deadly radioactive fallout produced.For orbit to orbit spacecraft, there are much better propulsion systems than Orion.

Gerb, I am afraid that Elukka is correct. Alloys like the one from the University of Minnesota do not convert heat into electricity. They convert a heat gradient into electricity. At the end you still have the heat to deal with.

This is discussed on the Atomic Rocket website in the "Thermodynamics" page (which I would like to include a link for, but Blogger.com thinks any links are spam)

I do encourage commenters logged in as 'anon' to sign a name or handle (like Gerb or Ferrell), to make the conversation simpler to follow.

Gerb - that paleo-Superliner car is way cool! Another concept ahead of its time.

My comment on Orion (the real one, with nukes) is my standard one - that the political incorrectitude is so colorful that it has distracted from the actual engineering issues of building a spacecraft that gets into orbit by deliberately nuking itself ~1000 times. :-D

Carbon nanotubes, or something on that line, may indeed be the stuff we are looking for - what I have sometimes called Super Nano Carbon Stuff. But it is way too early yet to know whether it can really fit the bill or not.

All in all - and anticipating a future post - I suspect if/when we DO find a relatively cheap way to get into orbit, it will be broadly Skylon-esque.

The reason I have been enthusiastic about Skylon is not because I am super confident that it will do all that it promises. I'm not sure I would bet on it being a true reusable SSTO, although of course I hope it will.

The thing is, even if structure, insulation, and so on does end up being a bit heavier than Reaction Engines Ltd. wanted, and that wipes out payload capacity entirely, the design can still be modified to something less pretty but still mostly reusable.

"almost SSTO" is the same as saying "requires only small boosters"

If the original design fails, I don't think it would be unreasonable to turn Skylon into a one-and-a-half stages to orbit design. Perhaps reinforce the wings and slap a pair of recoverable boosters on the outer edge of the engines. Small boosters ought to be easier to recover and reuse than large ones, since they are reaching smaller speeds and don't travel as far before detaching.

It would be an embarrassing design change, but you'd still end up with a quite nifty craft.

"Am I missing something? What's novel about bi-level train cars? They're common if not standard on US commuter rail."

Yeah, I was expecting the "bilevel" to refer to something weirder/cooler until I saw the pictures. We see trains like that all the time here in the Netherlands. I would not expect them to pose any major engineering challenges.

I appreciate them not so much because they can carry more passengers but rather because they give me an excuse to grab a high vantage point.

I think bilevel railcars are a relatively recent development in Europe, in part because of clearance issues.

I look at Skylon type vehicles (now) more as a development prototype. The same can be said of the X-37. These technologies are at the edge of our capabilities, and may never pan out.

But the only way to know the limits of our technologies is to test them. Whereas current practical booster development is not about the limits of the possible, but streamlining what we know works (e.g., expendable TSTO), so that it is somewhat cheaper.

Elukka, Nyrath. Yes, you're right. I've read the news from work, had no time to read original paper fully and fell for "completely new, was never done before" thing, because simple generation of electricity from temperature gradient is obviously older than me.

Nyrath, kudos for your site. I have it saved on my flash drive wherever I go and consult it from time to time. It is very useful.

And here goes offtop, for which I'm sorry (well, not *that* sorry, to be honest).We've had one bilevel car design developed in 1905 (that retro-style monstrosity), then two more in sixties (sovietstyle) and eighties (classyretro-futurestyle). They all were failures in commercial sense though and went to museums or junkyards. Our railway density is disgusting, like in some third-world country (Canada, for example ;)), so there's simply no demand for passenger traffic large and dense enough to make bilevel rail cars worthwhile.(Actually, if one considers rail length per population, Russia has 1,7 thousands of people per kilometer of track, Germany - 2,2, USA - 2,0 and Canada - 0,5. So we're not in as bad situation as it seems from the first glance. But the point still stands - there're major traffic jams on railway stations this summer because rail grid is not dense enough).The rail car from the eighties was made purely for tourist transportation, and the current one is made to transfer passengers to Sochi for 2014 Olympics. After that, I think, it too will go to some famous museum or nameless scrap pile. I may be wrong, of course.

Aaand I'm off derailing (pun unintended) the thread about spaceships. Though I do hope that my English was not bad enough to make the message unreadable or seem stupid.

A horizontal launch allows aerodynamic lift to do that work, but means more aerodynamic drag.A perfectly reasonable set of wings can manage a L/D ratio of 10+, which is equivalent to costing only 0.1g; that's a huge win for as long as you can stay in atmosphere (and, once you've built up a bunch of velocity, you can use your wings to curve up and go on a ballistic course). The big problem is that, well, wings are heavy and expensive, so the fuel fraction you can manage is dramatically reduced.

Maybe using a large(r) percentage of Super Carbon Nano Stuff (Graphine, Bucky-balls, Fullerine nano-tubes, etc), in the construction of a Skylon-like vehicle could reduce the weight to the point where it might actually be an SSTO...although I'd settle for a 'stage-and-a-half' to orbit.

The 80s vintage Russian car has the same overall arrangement as classic North American dome cars of the 50s - a truly wonderful way to travel by rail.

Unfortunately, in the modern era, Russia's great railroading strength - enormous distances - is fairly irrelevant to 'practical' passenger transportation. But St. Petersburg to Vladivostok would sure be a great cruise train ride.

I believe an L/D ratio of 10 is tough to achieve at supersonic speeds. But all in all, for settings in the plausible midfuture, I think winged is the best bet for (relatively) cheap orbital access.

I consider the benefits of concepts like SSTO, air-breathing or re-usability largely exaggerated.While it would be nice to have these features, the reality of space launch shows these solutions are either technically not feasible or not economical at current or near future tech levels.

Condsidering the currently only available manned space transportation system is Soyuz, a child of the 1960s, I would project 'near future' some 50 years ahead.

Depending on the production costs of a space transport, it looks like all the fuss required to recover and refurbrish the launcher (or parts of it) outweighs the cost to produce a new one.

I fully agree this is like throwing away a commercial jet airliner after one flight, but we have to accept that space travel will never be cheap or simple. We can optimize proven concepts (like TSTO or TSTO with additional boosters) but this is as good as it gets.

One word on any atmospheric augumented launchers:

The benefits gained are slim, while the technical challenges are huge. The total energy required to reach orbit is pretty high, only a small fraction can be gained from atmosphere.

Elevating the launch point (dropping from a high-altitude carrying plane) can maybe save 5% of the total energy.

Flying at Mach 5 at 30 km height (which will be pretty challenging!) is less than 20% of flying at Mach 25 at 200 km. And you still need a full-sized rocket to do the remaining 80% of the job.

So my guess for the next 50 years is we will stick with telephone-pole shaped launchers, burning fuels as today, with people and payload cramped into the tiny space on top. Space launches will stay rare and expensive.

I think the point about converting heat to electricity isn't the direct conversion but rather the ability to do it at room temperature. Or perhaps the ability to do away with the moving parts of a steam turbine. It is handy and can cut down on mass, but ya, you still need the radiators.

re: Orion lift off.I'm wondering if the concerns about fall out can be lessened by holding launches inside a natural cannon, like a caldera. Then be ready to seed the clouds to have the radiation washed out of the sky immediately after liftoff. Then, you also don't do your orbital burn until you've already cleared atmosphere. This limits your dispersal (hopefully) to a smaller area rather than a long trail of radiation. Finally, use fission-fusion (or pure fusion) so that your long half life emitters are minimized.

re: Difficult earth take off as story element. I actually enjoy that concept. Earth gets relegated to some pristine retirement goal for spacers. After a very expensive start up, space culture stays in space because it is too expensive to get back up. Hundreds of tons of space product would have to be shipped down the well to balance out the cost of getting a single person into space.

On things like Skylon: a jet with performance equivalent to an SR-71 can reach an altitude of 24 km and a speed of 1 km/sec in somewhere around 500s; based on the nominal range of the SR-71, doing so probably costs it 10-20% of its total fuel reserves, which seem to be around 50% of vehicle mass, so 5-10% of vehicle mass (in fuel) to reach 1 km/sec plus basically get out of atmosphere; figure it cuts 1.5 km/sec off of the delta-V required to get into orbit. With a 450s rocket, that would have taken 28% of your vehicle mass, so this looks promising at first. However, it looks rather uglier when you get down to it. To get 8.5 km/sec with a 450s rocket requires 85% of remaining mass to be fuel, so if we go with the optimistic (5%) value for jet fuel used to reach this state, we wind up at about 13% vehicle mass and 87% fuel mass.

This gives us 2% of vehicle weight to pay for wings and jet engines...

Air breathing launchers to LEO are a horrible idea. The air breathing works best in the early part of the launch, so it is competing against high density fuels (RP-1/LOX), which are optimal for the first stage of a rocket-based launcher.

RP-1/LOX engines have tremendous thrust/weight ratios, far better than any air breathing engine. And the propellant is cheaper than the all-hydrogen propellant the air breather is burning.

If we go to reusability, it will be by adding it to the first stage (or to the strapon stages) of an expendable launcher. This is much easier than recovering a stage from orbit, but still nontrivial.

How is it more efficient to carry both Hydrogen and Liquid Oxygen and burn those, than to burn the Hydrogen using Oxygen from the atmosphere?Essentially, what you're doing is trading fuel mass for engine mass -- the air breathing engine needs air intakes and pumps to get atmospheric oxygen into the reaction chamber, which adds mass, and since (fuel)+(21% molarity oxygen gas) is totally different from (fuel)+(100% molarity oxygen liquid), you're unlikely to even be able to use the same engine. The air breathing engine does have a large efficiency advantage at low speeds, but rockets are extremely dependent on keeping structural mass low.

The most efficient way to have an air-breathing stage on a rocket is to strap the rocket to the back of an airplane and call the airplane part the first stage, though air launch has its own set of technical challenges and you aren't saving all that much delta-V.

There's only so much oxygen in a given volume of air. You either have to make the engine bigger or accept a maximum amount of power per second, determined by the volume and mass of air you can sweep up.

"The third one you could design into the system potentially. (A maybe)"

How? If you want to mix X amount of fuel with Y amount of oxygen to obtain Z amount of thrust, if the air isn't dense enough and/or you can't sweep enough of it up, you're out of luck.

"The fourth one is a good point - but we were talking air breathing first stage only so it might not be such a concern."

Rockets work because they use high thrust first stages to get above most of the sensible atmozphere as quickly as possible. Air breathers can't do that, by definition. Remember, they have to achive roughly Mach 10 at 350,000 ft, or they're just a very complex and esoteric booster on a real rocket.

What's the feasibility of blasting off straight up, then looping around the moon to circularize your orbit? Again, I'm thinking nuke rockets, possibly orion style, but containing lift off in a column rather than an orbital streak.

You can easily control the mixture ratio by controlling the rate of fuel introduction to the combustion chamber. But you can't control the amount of oxidizer you receive from the air, because you can only scoop so much through a given intake area at a given airspeed. If you're already using all the available oxidizer, the only way to increase oxidizer supply is to make a larger, draggier intake.

The amount of oxidizer required for a given amount of impulse is in fact very well defined. The Shuttle External Tank, for example, contained 629 tons of LOX and delivered it to the engines at over a ton a second. This suggests that the ambient air is not a reasonable source of oxidizer supply.

WRT boosters, what I was pointing out about air breathers is that they are unlikely to make a completely sufficient first stage, either in terms of achievable altitude or achievable velocity. So even if you used them, they're function would be as boosters to a rocket that could achieve the necessary altitude and velocity.

I imagine that there is a sweet spot in the Lunar loop scenario where you use Earth gravity to slow you to Lunar loop velocities followed by a fall back to Earth acceleration which could easily circularize your orbit (or form an elliptical orbit as needed). The primary point of the operation is to confine fall out to a 'politically acceptable' level.

Conceivably, the Orion Booster might be a reusable launch platform where orbital vessels cirularize their orbits once out of the atmosphere. The now 'empty' launch platform orbits the moon and returns to Earth, using its massive shock absorber system to absorb the landing (presumably at sea and with ridiculously huge parachutes. Then we just let the ambient radioactivity fall off in the ocean before floating it back to the surface.

The inevitable mutant mermen could then be enslaved to harvest kelp to feed our hyperintelligent porpoise overlords. :)

"I imagine that there is a sweet spot in the Lunar loop scenario where you use Earth gravity to slow you to Lunar loop velocities followed by a fall back to Earth acceleration which could easily circularize your orbit (or form an elliptical orbit as needed)."

A free return trajectory around the Moon involves a 500,000 km apogee eliptical orbit that you can't launch directly into. To go straight up to the Moon would require accelerating real fast at a good fraction of 1g all the way, like in a Heinleinian torchship. Your delta-v from that would put you in a hyperbolic solar escape orbit that the Moon would barely effect.

That's why the original Project Orion crew ere thinking in terms of planetary exploration -- it was the only thing that made sense with all of that power.

The amount of oxidizer required for a given amount of impulse is in fact very well defined. The Shuttle External Tank, for example, contained 629 tons of LOX and delivered it to the engines at over a ton a second. This suggests that the ambient air is not a reasonable source of oxidizer supply.

===========================================It only suggests that if getting ~4.75 "tons" of air into the system is unreasonable.

If instead it is easy to get say 9 "tons" of air into a particular system using the same as the Shuttle's booster's need for oxygen, well then it is quite reasonable.

By undefined I did not mean how much oxygen was needed for combustion. I meant how much oxygen was needed for our unspecified lift off craft which has an undetermined mass, and undefined performance characteristics. And an only loosely specified mission.

================================================You can easily control the mixture ratio by controlling the rate of fuel introduction to the combustion chamber. But you can't control the amount of oxidizer you receive from the air, because you can only scoop so much through a given intake area at a given airspeed. If you're already using all the available oxidizer, the only way to increase oxidizer supply is to make a larger, draggier intake.===========================================

The the amount of air availible is not only scooped in but also drawn in with a impeller of some type. Commonly used in turbofan jet engines.

Its not much different than your car. Your car pass through enough air to cool itself without increasing the intake air flow by using a fan.

Sure if you are using all the air you can reasonably get and you still need more - you are out of luck.

The simplest way to model adding an airbreathing stage to a rocket is to simply use a separate stage for the airbreathing part -- i.e. it's a rocket launched from an airplane. There's a couple of problems with that. First of all, currently available aircraft really aren't all that fast, so they don't achieve much. Secondly, the aircraft stage is generally going to be much more expensive than the rocket (it's a lot more sophisticated hardware, tbh), so you really want it to be re-usable, meaning you can't use things like explosive bolts to separate the stages, and the aircraft part has to remain aerodynamic after separation. Third, stage separation while in atmosphere at several kilometers per second is just asking to have some atmospheric interaction disintegrate your entire vehicle, and if the second stage were stored internally (which is optimal for aerodynamics purposes) there's no way a payload bay door can be opened at hypersonic speeds.

If anyone could make something like hypersoar work, it would be a promising launch platform -- during the skip periods it's in thin enough atmosphere that you could actually open a payload bay to kick out a rocket.

Well, I still say SSTO is feasible; Rick (the blog owner?) has not said anything to convince me otherwise.

Let's say you can only launch 1 ton with it, but it can go all the way to LEO and all the way back down, launching and landing like an airplane. One metric ton is not a lot of cargo, but it is lots of passengers. That's 1000 kilograms or 2204 pounds, or 11 men weighing 200 pounds each. That's more people than the Space Shuttle could launch, but you are doing it with a *FULLY* reusable SSTO vehicle, meaning, launches and lands just like an airplane, and all you have to do to fly again is refuel.

And that's with what is, in my opinion, a very pessimistic estimate of how much an SSTO would be able to lift, and that's also assuming you use conventional rockets for your SSTO, as opposed to using a nuclear fission rocket.

That's 1/20 of what VentureStar would have been able to lift.

Presumably, you would launch cargo with other cheap technologies such as coilguns etc., since cargo usually can handle a lot more acceleration than humans, and in any case, your cargo launcher doesn't have to be "human rated".

According to the VentureStar entry on Wikipedia (which has a reference on the NASA web site), it was canceled not because anyone thought "it is physically impossible to do an ssto spacecraft", but because of engineering issues with the tank etc. Which says to me that it could be done.

Maybe reusable SSTO isn't the ideal way to get humans to LEO cheaply...but I don't think there is anything impossible about it. Again I don't have a college degree, I'm just a layman.

ORION nuclear powered ships were projected to launch from a giant tower structure built on Jackass flats, Nevada, in order to minimize fallout. The cost of building a 400 foot high tower capable of supporting a 10,000 ton ship (which would be vapourized on launch) would be pretty impressive, to say the least. An alternative plan would have been to set the ORION on a pancake of high explosive. The blast would lift the ship high enough to allow the first impulse unit (AKA atomic bomb) to fire above the ground, minimizing fallout. The pusher plate is proof against atomic explosions, so several thousand tons of plastic explosives would be shrugged off easily.

WRT looping around the Moon; Apollo (and Zond) spacecraft took three days to reach the Moon because if they went faster they would escape the Moon's gravity. A very powerful rocket ould have been needed to kill the velocity in a circularization burn, with added mass and complexity.

WRT reusable launch vehicles, I realized one idea which hasn't been mentioned is the BAC MUSTARD (Multi-Unit Space Transport and Recovery Device) concept, which used 3 or more identical airframes strapped together (several configurations were studied). Two or more would act as boosters, transferring remaining fuel to the center unit before separating and gliding home. The patent and drawings can be seen here:http://www.google.com/patents?id=OppcAAAAEBAJ&printsec=drawing&zoom=4#v=onepage&q&f=false

Re-reading Rick's post I think it I might be able to better explain what I mean. As he mentions you could potentially exchange some amount of vertical flight for lift/performance assuming you can tolerate the drag.

====================Now in the above example Type 2 is clearly superior to Type 1 in terms of payload. But of course the assumptions are arbitrary.

I am essentially assuming that for a mass penalty of 60 tons (wings/intakes/ hybrid air breathing engine) I can save enough LOX Mass to both compensate for added drag and increase my payload significantly.

It really comes down to - can you make the airbreather / lift body portion of the liftoff a net gain?

For example what if to make an airbreathing lifter in the Type 2 example above my vehicle needs to be 200 tons? Then I cant have any payload.

Also there is the added complexity of the Air-breather portion. Which I think could be a big factor.

The all LOX vehicle just burns Rocket Fuel+LOX all the way up. At whatever rate is required for each stage.

The Airbreather vehicle needs to draw in air, it needs to manage lift, which may mean a different amount of needed thrust- like an airplane does. At some point it needs to switch to a second stage that is LOX, or convert to running off LOX, etc.

But in the plausible mid-future it may be that technology allows for added complexity and mass savings which make the air-breather concept attractive. If it didnt we wouldn't see aerospace concerns suggesting air-breathing lift ideas.

"Flying at Mach 5 at 30 km height (which will be pretty challenging!) is less than 20% of flying at Mach 25 at 200 km. And you still need a full-sized rocket to do the remaining 80% of the job."

How does energy lost to gravity drag and atmospheric drag factor into this?

Paul D.:

"Oxygen is very cheap and requires little energy to produce, compared to hydrogen. So, saving on LOX by burning more LH2 (as an airbreather would) is penny wise, pound foolish."

It's mass we're worried about, not money. In a hydrogen-oxygen reaction, oxygen makes up 8/9ths of the fuel's total mass. In a carbon-oxygen reaction (not that anyone has seriously proposed a coal-powered rocket to my knowledge...), oxygen makes up 8/11ths of the fuel's total mass. Hydrocarbon fuels would fall in between (methane fuel is 8/10ths oxygen, for example).

Brian/neutrino78x:

"One metric ton is not a lot of cargo, but it is lots of passengers."

Passengers cost more than just the person's own mass, though. You need life support and furniture.

Granted, a shuttlecraft taking no more than several hours to reach its destination would need a lot less life support than a liner that needs to keep people comfortable for weeks. Still, dividing available payload mass by the average weight of a human being is not an accurate way to make an estimate of passenger capacity.

Thucydides:

"The cost of building a 400 foot high tower capable of supporting a 10,000 ton ship (which would be vapourized on launch) would be pretty impressive, to say the least."

The tower shouldn't be vaporized any more than the ship is. Especially since the nuclear bomb would be a shaped charge that's pointing away from the tower.

Unless you meant that the 10000 ton ship would be vaporized on launch, in which case, yeah, that's a realistic outcome of attempting nuclear pulse propulsion :)

There's only so much oxygen in a given volume of air. It doesn't matter how you try to draw it in, you eventually can't create a suction intake velocity than your air speed generates. That is in fact why all air-breathing stages are based on ram jets -- you get above about 2,000 mph and all you have is the amount of air you can scoop up due to your scoop area and your airspeed. If your air breathing stage, to be effective, needs more air than you can overtake by merit of your airspeed, then it won't work. Period.

Its probably hard to get across because the idea that you will run out of oxygen in a combustion engine in the earth's atmosphere (except at really high altitudes) is a bit of a stretch.

Is this supposedly a common problem in air-breathing engine concepts? And if so how do you explain scram jets? For example after some brief googling on scram jets and I am not seeing lack of oxygen as being a common design issue.

Usually (for most engines, including aircraft) the problem is the reverse. You have more air than you need and it is throttled.

However if it were the case that you could only get a fraction of the required oxygen needed for your engine, you could supplement it with LOX ..

Its the same basic arithmetic -- The mass needed for a little bit more LOX would be balanced against any savings gained by not needing to carry 100% of your oxygen needs with you.

"Its the same basic arithmetic -- The mass needed for a little bit more LOX would be balanced against any savings gained by not needing to carry 100% of your oxygen needs with you."

This seems bogus to me. The savings in a small percentage of your liquid oxygen load would be outweighed by the increased mass and complexity of the engine. Meanwhile, you still need the full complexity of the liquid oxygen tanks themselves.

Airbreathing can only conceivably be worthwhile if it allows you to save on all, or nearly all, of your liquid oxygen load.

My understanding is that air breathing SSTO is considered a good way to do it, but they usually need a high velocity in order to get enough air movement to use the oxygen in the air (again, these are engineering issues, there is no law of physics preventing SSTO, just present limits of human technology). That's where maglev launch assist could help; the maglev track would accelerate the vehicle to the appropriate speed where a scramjet would work, then it would take over. Still, I think a straight rocket SSTO would work just fine. :)

In fact, I would say that if you use a maglev to get to scramjet speeds, you might as well use it to get to orbital speed without using the rocket. Although that would probably rule out using it for human launches, since they usually need to apply a lot of acceleration to get it to fly all the way to orbit after release.

You may recall that all of the scramjet applications were to relatively small spaceplanes with 10,000 kg or so payloads. However much larger one might be able to go, there is a limit, because mass goes up proportionaly as the cube of the size increase, while air intake area only goes up by the square of that.

"Well, I still say SSTO is feasible; Rick (the blog owner?) has not said anything to convince me otherwise."

Rick is the blog owner But -- no disrespect intended -- I'm not sure why his word has any more weight than several others who have time and again presented reasons why SSTO is not viable.

"Let's say you can only launch 1 ton with it, but it can go all the way to LEO and all the way back down, launching and landing like an airplane. One metric ton is not a lot of cargo, but it is lots of passengers. That's 1000 kilograms or 2204 pounds, or 11 men weighing 200 pounds each. That's more people than the Space Shuttle could launch, but you are doing it with a *FULLY* reusable SSTO vehicle, meaning, launches and lands just like an airplane, and all you have to do to fly again is refuel."

First of all, it's highly unlikely that all one would have to do is refuel. Space Shuttle experience shows us that even with the best technologies* it costs a lot of money to reuse a launch vehicle 1st stage**, much less an entire launch vehicle.

Aside from that, you're ignoring the portion of payload that would have to be set aside for life support, crew garments (including pretty heavy pressure suits), structural crew accomodations (IOW cabin), etc. That's why Soyuz, at 7,000+ kg, only carries a crew of three.

*Let's not have any feedback about 70s technology. In a thirty year service life, especially with as much expensive between flight maintenance that was being done, if better technologies had become available, they would have been retrofit to the Shuttle fleet.

**That was the effective role of the Shuttle as a launch vehicle, regardless of the incorporation of the cargo bay and crew accomodations.

"And that's with what is, in my opinion, a very pessimistic estimate of how much an SSTO would be able to lift, and that's also assuming you use conventional rockets for your SSTO, as opposed to using a nuclear fission rocket."

Given the tens of thousands of skilled people who work in the industry who don't seem to be able to figure out a better way, you're opinion, well...

"According to the VentureStar entry on Wikipedia (which has a reference on the NASA web site), it was canceled not because anyone thought "it is physically impossible to do an ssto spacecraft", but because of engineering issues with the tank etc. Which says to me that it could be done."

And I've already written on these comment pages that Jerry Pournelle related at the time that the tank problem was just a convenient excuse. They were adding weight to the vehicle to make it aerodynamically stable, and basically running out of payload fraction.

"Maybe reusable SSTO isn't the ideal way to get humans to LEO cheaply...but I don't think there is anything impossible about it. Again I don't have a college degree, I'm just a layman."

Yes, you are. So am I. But I study the subject hard and have learned that a major "get it" thing is that the people who do this for a living know what they're doing. If they could find an economical way to do SSTO, they would. They can't, and there's nothing in the real world tea leaves that says they can. That's just a fact.

No disrespect, but you're reaching. Whatever the size limit is, it exists, because it's simply a mathematical fact that the square/cube curves diverge. Eventually they'll diverge to the point that air breathing is not viable.

Also, please forget about suction helping out. There's an airspeed limit to that too. I mentioned that eventually airspeed would make a difference in suction effectiveness. There's also an internal dynamics issue with higher sirspeeds, to the point that turbine compressors don't work. You have to do ram compression or nothing.

I was allowing for the end of suction at a certain speed, basically allowing for your earlier comment. Perhaps you misread what I said there.

The drawn air would be for the slower speeds.

=====================Tony,No disrespect, but you're reaching. Whatever the size limit is, it exists, because it's simply a mathematical fact that the square/cube curves diverge. Eventually they'll diverge to the point that air breathing is not viable. =======================

Who's reaching here? You don't know the maximum amount of air the undefined vehicle can reasonably get any more than I do.

An air-breather doesn't need to have infinite scalability. The point where the amount of air I can get versus payload is extremely important.

At 10,000 kg you have some utility.

At 100,000 kg you have more utility.

I may not need 200,000 kg ...

This square/cube relationship you are describing (assuming it is the main factor) intercets at some point X. Sure the ability to scale up drops off rapidly after point X.

But a lot depends on what X is.

If X plugged into the rest of my equations gives me a payload that is more than sufficient for the design needs- it doesn't matter that it will drop off at some payload it doesn't need to carry.

Your car can't get infinite air into the engine either. But it doesn't matter because you don't need infinite air to make it run. You need some finite amount.

"In fact, I would say that if you use a maglev to get to scramjet speeds, you might as well use it to get to orbital speed without using the rocket."

While you might be able to use a very large maglev to hurl something into orbital altitude, you still need an actual rocket engine to circularize your orbit when you get there. Otherwise you'll just fall back down. So you'd have a two-stage system, with the static megastructure replacing the first stage rocket, but not the second stage rocket.

One thing you might, in theory, be able to do without a rocket engine of any sort, is use a maglev to launch a probe on a trajectory to another planet or moon, then use aerobraking or lithobraking once you arrive there, while at no point actually orbiting anything except the sun. That'd require a pretty powerful maglev!

Basically this craft would be of some size, with a payload limited perhaps by the maximum air it can get, perhaps by other factors.

It would launch from a standing start, or be assisted by some ground propulsion.

The Air-breather in turbofan mode would begin to pick up in speed and altitude along a carefully chosen flight path.

As it ascended the engine would move to function like a ramjet - picking up more speed.

As it continued up it would move to function like a scramjet picking up more speed.

If it became air starved at any point in this venture additional oxygen would be provided from LOX tankage.

At some point it would move to pure rocket mode and go to orbit.

----------

I of course am not a aerospace engineer so I do not know what the vehicle size requirements and mass limitations of that system are. I suggest that any actual aerospace engineer would tell you they don't either, although they would have a better idea what the ranges might be.

I only know IF that system can save enough O2 mass VS a pure rocket system by a combination of lift and the fact that it can consume massive quantities of atmospheric air during its flight .. then the system could be viable at some certain size.

For comparison, the International Space Station is 187 tons (and that's if you launch it all in one piece, rather than assembling components in orbit as we have done). The biggest rocket built so far, Saturn V, had a maximum payload 118 tons. The biggest one currently in operation, Delta IV Heavy, is 23 tons. SpaceX's Falcon XX, if developed, would only be 140 tons. (See here.)

So 100 tons per launch should be enough for pretty much anything we're doing in space right now, and is probably overkill for many applications. In fact, this data is convincing me that 10 tons is already pretty good. Your space superdreadnaughts will still have to be assembled in orbit, though.

You know, something occurs to me. When talking about rockets, people usually picture towers that go straight up, while when talking about airbreathers, people usually picture spaceplanes. What do people think of rocketplanes that carry their oxidizer but use wings to aid in lift, or airbreathing "rockets" that point up rather than sideways and "hurl" themselves out of the atmosphere using speed gained while inside it?

Cost is the relevant figure of merit. And cost does tend to reflect energy input, although not precisely. The air breathing booster will use more energy, since it loses more to drag and gravity losses. Liquid hydrogen, per unit mass, embodies much more energy than does LOX.

Anyway, I repeat: air breathing is lousy for launchers. Trade studies that consider air breathing consistently, I am told, optimize to designs in which the air breathing fraction of propulsion is zero.

Interesting - reading that bit you linked suggests a lot depends on the Thrust/Weight Ratio of the air-breathing engine being considered. With the author stating that its too low for air-breathing engines.

But T/W is going to vary with materials technology. Although how much?

I still don't see hydrogen cost being as relevant as you seem to.

The most important thing I think is increasing the mass ratio of payload to Fuel+Oxidizer

As it says in the post with a 6:1 Ox / fuel ratio -- you are using 6 tons of LOX for every ton of fuel in the rocket.

So even if you triple your fuel consumption you have the potential for mass savings.

---------------

Hydrogen as a commodity is not going to "cost" as much in a plausible mid-future as it does today. Any mid-future supporting space colonization needs to have solved our current energy issues.

And take the enormous draggy heavy LH2 tank to orbit with you. Remember that while LOX is most of the mass of the propellant in a LOX/LH2 rocket stage, the hydrogen tank is most of the volume. LOX is 16.8 times denser than LH2 (at their respective boiling points at 1 bar). Heroic measures like using slush hydrogen don't remove the problem.

The appallingly low density of LH2 is also why LOX/hydrocarbon stages can achieve such good performance, even with the lower specific impulse than LOX/LH2, and why LOX/hydrocarbon engines are easier to operate at higher pressure (the fuel pump has less work to do).

Finally: the low density of air means the low thrust/weight of air breathing engines should not be a surprise, especially hypersonic engines, and especially engines that are intended to operate over a whide range of mach numbers (and hence will likely require variable geometry). In general air breathing is lousy for applications that don't operate in a narrow range of speeds over long periods ("cruisers"), or that operate at extremely high speed. Cruise missiles, perhaps even Mach 8 hypersonic ones, ok; "accelerators", no.

But -- no disrespect intended -- I'm not sure why his word has any more weight than several others who have time and again presented reasons why SSTO is not viable.

This may be as good a place as any to note that while several commenters clearly have a sci/tech background, so far as I can tell, no one who comments here is actually a rocket scientist. (Or rocket engineer, for those who take their pedantry in straight shots.)

Which is kind of a bummer. But the relevant point is that appeals to authority (emphatically including mine!) have extremely limited traction.

Keep in mind with your launch tactics that faster launches require more acceleration. People will be a limiting factor in some cases, but often it is the payload (like a delicate satellite) that puts an upper cap on acceleration. Also, the higher your acceleration, the more structural support is needed for lift off. That is added weight, which further limits your payload. The space shuttle topped out at about 3 G's of acceleration, actually having to throttle back at one point to avoid over stressing the wings.

The ISS orbits at about 7700 m/s, so rounding 3G's to 30 m/s^2, it would take 257 seconds of acceleration. That would also take a straight linear accelerator 988 km long, about the distance from Chicago to Washington DC. It would also need to be a vacuum due to heat build up.

By contrast, a 'durable goods' launcher, capable of lofting with 9 G's of acceleration could be build into a 'compact' torus of only 140 km diameter or straight line 330 km.

One of the benefits of this is that it is fairly easy to weaponize and thus get funding from the military. Also, the components are likewise useful in different industries. However, it is still quite clear that they would function better in a vacuum and on worlds with lesser gravity.

Passenger mass. Commercial airliners seem to carry roughly 4 passengers per ton of cargo payload capacity. But Orion (the capsule, not the baseball with a kiloton-yield bat) is about 2 tons per passenger.

The first case represents the trade-off against cargo in the pressurized hold of an airbreather. The second case represents the trade-off between a recoverable passenger capsule and a satellite payload.

I think the problem for airbreathers is not precisely 'not enough air,' but getting enough air, at very high speed, without an intolerable heat bath.

Economic cost is the basic figure of merit we are concerned with, but it will depend in part on factors such as traffic volume. Indeed, therein lies the rub, because pretty much every proposal for cheaper spacelift relies on greater volume.

Milo, I don't count that as two stage because the rocket is not activated until you are already in space. Plus, the maglev part is not a rocket, so it wouldn't be two stage anyway; there's only one rocket stage. SSTO just means you get into space without having to use a second rocket stage.

Tony, it's good that you finally admit you are a layman on the subject of space travel, too, and therefore don't "get it" any more than anyone else.

The fact remains, the problems with VentureStar were related to engineering and technology; there is no law of physics preventing SSTO from working, any more than the laws of physics changed between 1940 and 1970 so as to permit Project Apollo (and the laws of physics did not change after the last Apollo mission). If you used a nuclear fission rocket, for example, SSTO would be no problem at all. Nuclear rockets have double the ISP of H2/O2 and greater thrust (many variants on NERVA had T/W ratio greater than 1). With chemical rockets it is more challenging, but certainly not impossible. If only 1% can be payload, that just means the overall size of the vehicle has to be proportionate to that.

And I am *not* "ignoring" life support etc. I included it in the 1 ton figure.

Even if you can only lift THREE people with an SSTO, it would still be an SSTO, and it would still not violate the laws of physics. Even if only one person could go, it would still be SSTO.

And I don't think it is "extremely unlikely" that you could relaunch it just be refueling it. They do that with airplanes all the time.

SA Phil said:"It would launch from a standing start, or be assisted by some ground propulsion.

The Air-breather in turbofan mode would begin to pick up in speed and altitude along a carefully chosen flight path.

As it ascended the engine would move to function like a ramjet - picking up more speed.

As it continued up it would move to function like a scramjet picking up more speed.

If it became air starved at any point in this venture additional oxygen would be provided from LOX tankage.

At some point it would move to pure rocket mode and go to orbit."

You have just described the SABER engine of project SKYLON. You should read their website (sorry, I can't find the address at the moment), they go on to discribe the active heat management, lift, and light-weight/high-strength construction. They also mention that the vehicle would have a fixed number of flights that seem to equate to 2-3 years of service; much shorter than a typical airliner, but much better than a single-use rocket. Again, I don't know if it will work out, but we should know in a few years when they fly their prototype.

"Which is kind of a bummer. But the relevant point is that appeals to authority (emphatically including mine!) have extremely limited traction."

It depends on the authority you're appealing to, Rick. My opinions are abased on recognized sources of engineering and historical knowledge -- Fundamentals of Astrodynamics (AKA Bate, the primary orbital mechanics text at the USAF Academy for many years), Encyclopedia Astronautica, and Atmoci Rockets (which is not widely recognized, but generally accepted around here). Others' opinions against SSTO seem to be euqally well grounded. If someone wants to challenge our interpretations of those sources, they are perfectly welcome to, but, to borrow a turn of phrase, they're not going to gain any traction unless they make their challenges within the context of those sources or superior ones.

"Tony, it's good that you finally admit you are a layman on the subject of space travel, too, and therefore don't "get it" any more than anyone else."

Don't put words in my mouth, shipmate. I've always admitted I was a layman, but I've never suggested or accepted that all laymen are equivalent in knowledge. But in any case, this isn't personal. It's whether any given opinion represents the real world facts or doesn't. I'm perfectly sanguine to have that judged by the readers.

"The fact remains, the problems with VentureStar were related to engineering and technology..."

You're confusing physical possibility -- SSTO just may be physically possible, barely -- with technical, economic, and political viability. And there are plenty of technical, economic, and political reasons why SSTO is simply not practical.

"And I am *not* "ignoring" life support etc. I included it in the 1 ton figure."

No you're not. You figured only passenger mass within your 1 ton.

"Even if you can only lift THREE people with an SSTO, it would still be an SSTO, and it would still not violate the laws of physics. Even if only one person could go, it would still be SSTO."

And if an expendable system could still do it for less money, SSTO would be mistake.

"And I don't think it is "extremely unlikely" that you could relaunch it just be refueling it. They do that with airplanes all the time."

Probably a better place to put time and effort is to make the payload and space capsule as light as possible, so we don't need such massive rockets and highly stressed engines to achieve orbit.

The other issue is to strike a balance between high density fuels like Kerosene and high energy fuels like LH2. I would guess that Methane might make a good compromise, being denser than Hydrogen and does not require such complex materials handling issues (i.e. it is not a deep cryogenic fuel, nor does it have as many issues with seeping out of the pores of the metal or embrittling the metals). The smaller fuel tank would pay off in reduced size, tank mass and aerodynamic drag.

Depending on which source you choose to believe NERVA type engines may or may not be powerful enough for SSTO use. The flight ready NERVA XE was not designed to act as a boost stage rocket, but the Peewee could put out 4000MW, which in theory could be used as a boost stage engine. How much extra mass you needed to add as radiation shielding makes it difficult to say; most designs of the era used traditional "totem pole" architecture to maintain distance between the reactor and the cargo, and the hydrogen remass was expected to absorb some of the radioactivity being emitted as well...TIMBERWIND may also have been boost capable, it would have been much lighter than the corresponding NERVA design from 20 years earlier.

"Probably a better place to put time and effort is to make the payload and space capsule as light as possible, so we don't need such massive rockets and highly stressed engines to achieve orbit."

While miniaturization is very useful for many things, there are some things that just can't be miniaturized. Humans are one of them. The resolution of things like telescopes depends on the size of your lens. A Mars rover needs a certain amount of size just to be able to effectively climb over rough terrain and to not get picked up and slammed around by freak windstorms. And as has been pointed out earlier, more miniaturized computer architecture is more vulnerable to cosmic rays.

Have you considered a nuclear or laser thermal steam powered rocket? I know the nuclear salt/water rocket design has the kick needed for launch, but it kinda irradiates the planet in doing so. But switching to a short half life reactant or a closed system (some how), could give the lift off thrust we need. From what I understand, the Isp kinda sucks (190 sec), but I'm not proposing it for interplanetary flights, just the heavy lift to orbit.

Any such rocket would be terrible, with an Isp inferior to even LOX/hydrocarbon chemical engines. Most very high temperature refractories cannot withstand a high temperature steam environment (carbon converts to H2 and CO, for example).

If you want such an engine, you'd use ammonia as the propellant. Not only would this give a reducing environment, but it would largely convert to nitrogen and hydrogen in the engine. T/W for the nuclear case would still be lousy, though.

LOX/LCH4 has a better maximum practical Isp, but not wildly better -- 360 sec vs 340 sec (that relatively heavy carbon atom is probably the poison pill). On the other hand, it has a lower density than kerosene, meaning that extra tank structure probably wipes out any Isp advantage. The addition of cryogenic properties makes it a non-desirable fuel.

The steam powered rocket uses 'external combustion', by applying heat to water to cause pressure difference and expansion. My guess is that you actually want to super heat the water to prime it, that means you're not dumping heat into the phase change during the time sensitive portion of the flight. If you can shift the heat generating device off the rocket, and just have the heat capture and transfer mechanism, I'm hoping you can get the T/W ratio up to useable levels.

So, perhaps a laser-thermal system where the rocket launches out of a mountain peak and lasers/masers target it for an energy source. As it gets further away, you lose focus but your weight also drops way off, which hopefully allows for an even acceleration curve.

The hope here is that you're not launching nuclear bombs into the sky and your propellant is cheap and inert. The laser systems, while critical for launch, could be re purposed for boosting existing satellites and the same technology could be used for power transfer from orbiting solar collectors. That same technology could then be used for 'civilian' uses such as beamed power to tankers so that they can just use steam boilers for transit. Furthermore, on land where weight isn't an issue, molten salt power stations could store the power in the form of heat so that they still produce power at night.

Tony, I do agree with you that there are reasons other than engineering and physics why the idea of SSTO may not viable. I was arguing with the concept that it is somehow impossible, for engineering and/or physics reasons, for any organization to do it, that's the part I disagree with.

Before the Wright Brothers, people thought that heavier than air flight would never be practical, but it didn't turn out that way. History is full of examples like that, even in the Navy. Nuclear powered ships and subs, ships made of metal, determining longitude at sea (the breakthrough was accurate mechanical ship's chronometers), etc.

My interest here, and what I think the government's interest and/or goal should be, is to make access to LEO as cheap as possible. I imagine that there will be multiple methods of launch (to LEO) in the future: SSTO, fully reusable multistage rocket (all stages recovered and reused), extremely cheap expendable rockets, coil guns (for cargo), balloon launch assist, maglev launch assist, aircraft launch, etc.

And...rather than putting words in your mouth, I thought you admitting to be a "layman", which is what you did say? A layman is a layman, right, if neither of us has specialized knowledge in that particular field, then we are pretty equal, that's what I meant. That's what the word "layman" means, that you don't have special knowledge in a given field, more than the average person would have, at least imho. Maybe you meant it in a different sense. :-/

I notice my comments on this blog seem to be very controversial... :-O

guys, like I said, there were versions of NERVA that had high T/W rations. For example I have read that "DUMBO" had a T/W of like 30 to 1. It was never funded for a test because it needed a different type of nozzle than NERVA. look at the drive table from atomic rocket:

http://tinyurl.com/3rxbkmz

in the NTR DUMBO entry it says thrust is 3.5 million newtons and mass is 5 metric tons.

Such a drive should be able to take off from the surface of the Earth with a single stage imho? But I'm sure people will disagree, as they usually do lol.

"Tony, I do agree with you that there are reasons other than engineering and physics why the idea of SSTO may not viable. I was arguing with the concept that it is somehow impossible, for engineering and/or physics reasons, for any organization to do it, that's the part I disagree with."

Physical laws do make SSTO impossible as a matter of practicality impossible, even if there is a technical way to accomplish the task. You're just going to have to give up on the idea that physical laws have nothing to do with it. Engineers work with physical laws, and if they tell you it's going to cost too much to be worth doing, it's not because money isn't cooperating, it's nature.

"Before the Wright Brothers, people thought that heavier than air flight would never be practical, but it didn't turn out that way. History is full of examples like that, even in the Navy. Nuclear powered ships and subs, ships made of metal, determining longitude at sea (the breakthrough was accurate mechanical ship's chronometers), etc."

You're suggesting an iron law that if you can dream it, you can do it. Well, we still don't have personal rocket packs or helicopters in every suburban garage. We have personal computers, but we don't have sentient family robots. We can send a probe to Pluto, but we don't have cities on the Moon. You're engaging in confirmation bias, pure and simple.

"My interest here, and what I think the government's interest and/or goal should be, is to make access to LEO as cheap as possible."

The government's interst is in accomplishing tasks that private concerns don't want to fund. If private concerns wanted and thought they could get significantly cheaper access to space, they could get it for themselves -- they would already have it. THey know the government won't pay for that. What the government pays for is exploration and some basic research in aeronautics/astronautics. That's it.

"And...rather than putting words in your mouth, I thought you admitting to be a "layman", which is what you did say? A layman is a layman, right, if neither of us has specialized knowledge in that particular field, then we are pretty equal, that's what I meant. That's what the word "layman" means, that you don't have special knowledge in a given field, more than the average person would have, at least imho. Maybe you meant it in a different sense. :-/"

Layman means that you're not professionally qualified or experienced. It does not mean you are doomed to knowning no more than others in the same status, nor does it mean you can't learn. The basic physics andengineering principles of astronautics are accessible to anybody with the capability to learn. Some people put in the effort, some don't.

"I notice my comments on this blog seem to be very controversial... :-O"

Not controversial, just uninformed. Not all laymen investmens of time are equal. Some laymen avail themselves of good sources that teach realistic knowledge. Others spend their time with popular magazine articles, coffee table books, and faux expert web sites like nasaspaceflight.com.

Have you considered a nuclear or laser thermal steam powered rocket? The limitation on thermal rockets is that they can't run so hot that they melt the engine, which depending on engine structure usually limits you to around three times the speed of sound in the gas. Chemfuel rockets are actually operating pretty close to that limit; if I'm doing the numbers right, a temperature limit of 2,500K would give a maximum of 460s for water vapor and 290s for hydrocarbon (C3H8) combustion products. Thus, if you want to significantly exceed the performance of chemfuel rockets, using a physical nozzle, you are pretty well forced to use hydrogen gas -- with the same temperature constraints, hydrogen gas can reach 1,100s or so.

That said, it's not like hydrogen gas is impossible to manage. The other problem is that we simply can't build the power source. A thermal rocket capable of putting one ton in orbit (where that 1 ton includes the entire mass of the rocket, not just the payload), assuming a maximum specific impulse about 1,000, requires about 200MW drive power for a fixed exhaust velocity design, slightly less for a variable exhaust velocity design. Neither nuclear power sources capable of producing 200 MW in less than a ton, nor lasers capable of producing 200MW constantly, are currently available or even close.

Phoebus-2Scientists increased power density even further with the Phoebus-2 series. However, a limiting factor proved to be the cooling in the aluminum pressure vessel. Despite this limitation, tests run with the Phoebus-2 were considered highly successful. The final Pheobus-2 test in June 1968 ran for more than 12 minutes at 4,000 megawatts—for its time, it was the most powerful nuclear reactor ever built.

PeweeConsidered as a smaller version of Kiwi, Pewee was fired several times at 500 megawatts to test coatings made of zirconium carbide. Scientists also increased Pewee's power density. Easy to test and compact, Pewee was ideal for unmanned scientific interplanetary missions.

So we have potentially compact and powerful engines, although for most purposes they would need to be used in space rather than Earth to Orbit.

The Project Timberwind concept was based on a particle-bed reactor using tiny uranium carbide pellets as fuel to heat hydrogen propellant. The exhaust would have been highly radioactive. Preliminary designs had been selected but no prototype components had been tested before the program was canceled. (from here). It's being generous to assume that it would actually work, and even if it did the radiation problems would make it not viable as a launch tech. In general the problem with nuclear thermal is getting adequate power without having any direct contact between the fuel and the propellant and without your fuel melting, you can achieve essentially arbitrary power from the fuel but there's much tougher limits on how much you can safely get out of it.

NTR's produce radioactive exhausts, so are non starters for launch vehicles for environmental reasons. Issuing a blanket statement that NTRs are incapable of being used as a launch engine is wrong; not everyone has the same sort of scruples that we do, and circumstances might compel some players to go for the nuclear option. (We might not even be in a position to object to the use of NTR launch vehicles).

Now most historical discussions on the use of American NTRs was based on the use of these as powerplants for space applications, so the need for such monsters as Peewee 2 or TIMBERWIND 75 was much reduced. The most common ideas floated back then were space tugs to move heavy payloads around cis lunar space (including parts to build a Moonbase) and to propel the Mars mission.

While deep space missions in the mode of "2001" would also have been possible, I haven't seen any serious discussion from that era (oddly, the somewhat older and more speculative ORION project had pretty clear plans about going to Mars in the 1960's and reaching Saturn in 1975!)

Since humans are not capable of miniaturization, I suspect the PMF will be dominated by swarms of small probes and robotic vehicles, with their human operators watching on computer monitors and occasionally inputting updated commands. If there is a need for human presence to fix things, I would expect small X-37 type spacecraft to deliver a repairman for a short mission (2-3 days max) for items in LEO. If there is a plausible need or desire to build a Moonbase, the humans wil probably be in a small radiation shielded bunker teleoperating swarms of robots, and fixing things in a garage rather than going out to explore.

NTR's produce radioactive exhausts, so are non starters for launch vehicles for environmental reasons.NTRs don't have to produce radioactive exhaust; neutron activation of hydrogen is so rare as to be essentially ignorable (crashes are, of course, a concern). Unfortunately, high specific power NTRs have the fuel in direct contact with the reaction mass, which means you'll get fuel spread downrange, and that will be radioactive. Also highly wasteful of nuclear fuel.

Even if a working nuclear fission motor with LV level impulse could be developed, what country that could do something about it would allow it to be flown through the atmosphere? We should be adequately educated by now that accidents with nuclear stuff happen, even when we think they can't. And with rockets we know pretty d@mn well that they can.

"If there is a plausible need or desire to build a Moonbase, the humans wil probably be in a small radiation shielded bunker teleoperating swarms of robots, and fixing things in a garage rather than going out to explore."

I don't see why. Movement in space is difficult, but movement on the surface of the moon ("walking", as we call it) is not. A spacesuit is not a notably more complicated piece of equipment than a versatile robot swarm, and is not notably heavier than the humans and their life support are to begin with, and is definitely not heavier or more complicated than the factory equipment to construct and refurbish the robots in your moon garage. There are things that are just much easier to do with proper hands than with remote-controlled robots.

If all the humans do is remote-control drones rather than interacting with stuff personally, they might as well be on Earth. The lightspeed lag to the moon isn't that bad.

Ultimatly, the reason for a human presence on the Moon in a robotic environment is to act as the "Maytag Repairman" and fix the things which designers did not anticipate going wrong or that robots cannot fix themselves. (Maytag is a brand of household apliance which is reputed to be so dependable, the repairman sits idle in his office waiting for service calls according to a series of ads on Canadian TV).

Since the Moon is a pretty harsh environment for machinery, it will be more cost effective at some point to have a repair depot on site rather than constantly send new machinery to replace stalled, broken or unexpectedly damaged equipment. The Lunar repairmen (and women) won't be doing much EVA; you can picture them in "clean suits" going into the "garage" after it is pressurized and doing routine maintainence and repair work. For harder jobs they may need a "tow truck" to go get the broken machine and deliver it to the garage. There will probably also be a scrap pile outside which is occasionally raided for parts.

They may do some surface walks from time to time, but company regs and the insurance will limit this to a minimum.

Looking at Spacex plans for Making Falcon Rockets Reusable to get to $50 per pound launch costs

Elon Musk at Spacex has spoken several times about making the Falcon launchers reusable.

Recently Spacex indicated that they have designs worked on on paper (computer models) that would solve the issues of reusability and get launch costs down as low as $50 per pound. The Falcon Heavy could get costs down to $1000 per pound.

Previously Musk said SpaceX will continue to pursue greater reusability -- "a fundamental long-term ambition", saying that a fully reusable system "is pivotal" to his intention to support the foundation of a sustainable human civilization on another planet. He points out that the cost of propellant for a Falcon 9 flight is around $150-$200,000, compared to $50 million for the vehicle, "so there is efficiency to be had".

The latest plan appears to be from brief comments* restart the engines in order to slow down the first stage (not a full flyback) and shed some of the velocity.* Less payload for fuel for restarting rocket to slow descent* better thermal shielding and increased structural margins for recovery which also reduces the payload.* the benefits of reusability should be a lot more than the decrease in the payload that goes up each time.

"By [Falcon 1] flight six we think it’s highly likely we’ll recover the first stage, and when we get it back we’ll see what survived through re-entry, and what got fried, and carry on with the process. ... That's just to make the first stage reusable, it'll be even harder with the second stage – which has got to have a full heatshield, it'll have to have deorbit propulsion and communication.

So a iterative process of increasing heat shielding.

Both stages are covered with a layer of ablative cork, have parachutes to land them gently in the sea and have been marinized by using materials that resist salt-water corrosion, anodizing and paying attention to galvanic corrosion.

While many commentators are skeptical about reusability, Musk has said that if the vehicle does not become reusable, "I [Elon Musk] will consider us to have failed

NASA spaceflight forum covered Spacex ambitions in 2009

One of the goals I [Elon Musk] have for the Falcon 9 – which will take us many launches to achieve – is to have the vehicle out of the hanger and into the air in under 60 minutes.

“With Falcon I’s fourth launch, the first stage got cooked, so we’re going to beef up the Thermal Protection System (TPS). By flight six we think it’s highly likely we’ll recover the first stage, and when we get it back we’ll see what survived through re-entry, and what got fried, and carry on with the process.

“That’s just to make the first stage reusable, it’ll be even harder with the second stage – which has got to have a full heatshield, it’ll have to have deorbit propulsion and communication.”

Musk also spoke about his wish to enable the first stage with flyback capability, but added that he would require a large sum of cash to achieve that goal.

“Any pound you use for reusability and re-entry (on the second stage) is a pound subtracted directly from payload, whereas first stage it’s a five to one ratio. This is a problem we’re trying to solve incrementally, but most exciting thing I’ve love to do is a flyback first stage. We’re just missing the billion dollars of capital it would take to try to do that.

Tony, there is no law of physics preventing someone from having a helicopter in their backyard. That's just political reality. My sovereignty ends when it intersects with your rights, and then the government gets involved.

I'm not uninformed at all. The only difference between you and I is that you might know a little more math than me. As I said, I don't read Heinlein, I read Ben Bova, Stephen Baxter, Charles Sheffield, Poul Androson (spelling), Arthur C. Clarke. They are all Hard SF writers (and they write books for adults, contrasted with Heinlein, who apparently wrote mainly books for kids) and most have degrees in physics and/or engineering (Baxter has degrees in math and engineering, and interviewed a lot of NASA engineers and astronauts as research for his books). I am 33, and Heinlein was not popular anymore when I was growing up. I did grow up on Star Trek and Star Wars, and YES, I do know that according to present physics, warp drive, gravity floors, transporters, etc. are not considered plausible (yes, I have read the book The Physics of Star Trek).

SSTO is not "childhood fantasy" in the sense that warp drive is!!!!

SSTO (and other means of achieving the Ben Bova/Arthur C. Clarke/star trek/star wars future) is analogous to making a ship out of metal, which, as a Navy man, you know was once considered the same way you regard SSTO. There are no fundamental laws of physics preventing it, rather it is a matter of engineering, as well as economic practicality.

In any case, like I said, SSTO is just one of many technologies which I expect to see in the future as companies compete to drive down the cost to get to LEO and beyond.

My fundamental position is not necessarily "SSTO is practical", but rather "it is practical, and inevitable in the long term, for it to become so cheap to get to LEO that one will be able to order a ticket there for the same price that one now pays to travel from San Francisco to London on a commercial jet aircraft, that is to say, a future when billions of people are living in space and other celestial bodies is inevitable." And I know you will disagree, but look at how much has already been accomplished by SpaceX et al.

I'm peeking at this thread I would normally ignore since I was commenting at the other.I don't know much about launching systems and I hate to agree with Tony but I think know enough to have a rough idea of what works.NASA is not the only game in town as far as launching is concerned. You whine about it but it's the only organization which seriously tried something like an SSTO (a serious mistake). Russian launches are done with rockets. French launches are done with rockets. And get this: commercial launches are done with rockets.

You people need to get around this: the cost of access to LEO is not an obstacle to humanity's future in space, only to fantasies.The reason there's not a billion people living in Antarctica isn't that it's more expensive to get there than to cross the Pond!If the day ever comes when humans can not only survive for a while but actually live out there, it's only a matter of time before the off-planet population reaches 1 billion, even with today's launching costs.Everything humans need to live can in principle be built out there. What needs to be launched is enough people and gear to jump-start a civilization in space as well as diverse enough genetic material in the form of frozen gametes.If the technological and social developments necessary to live out there were available today (they're not going to be for the foreseeable future), a space civilization could be launched from Baikonour with what basically amounts to cold war technology.

Preposterous. SpaceX is simply a company trying to undercut the established industry leaders in launch services. They're doing the same thing as Boeing and LockMart with medium lift, just at a lower cost structure. (And there are plenty of good, down-to-earth (every possible pun absolutely intended) business reasons why SpaceX won't be able to maintain their cut rate cost structure indefinitely.) NASA in 1969 was mounting a cutting edge exploration campaign. SpaceX can't and won't do that, simply because it's not in their business plan to do so, and nobody would pay them to do it if it was.

"This should be expected, because space is analogous to The High Seas, and most ships on The High Seas are private. :)"

Space is manifestly not analogous to the high seas. Private ships on the high seas are apendages of a business model that has nothing to do with the sea, except for the fact that it makes a relatively efficient medium for transporting goods. Space as a transportation medium is not relative to anything but itself. There's no competing medium of transportation. There's no trucking, railroads, or aircraft. It costs what it costs. And that cost is expensive relative to any means of transportation on Earth. It's so expensive that private spacecraft can only be afforded by large corporation or institutions. Manned spaceflight is so expensive that only governments can afford it. Those are simple facts. Denying them doesn't change them.

"Tony, there is no law of physics preventing someone from having a helicopter in their backyard."

The difficulty and expense of operating helicopters (which limits how many can own and operate them) and the safety concerns about their use in heavily built-up areas (which limits when and where people will be allowed to use them) has everything to do with the physics of flight. If they were as easy and cheap to operate as cars, and if a mishap was no worse than a fender bender, we would see plenty everywhere. Since they are as hard and as expensive to operate as any other aircraft, and since thousands of pounds of wreckage falling out of the sky is way worse than a fender bender, you see few helicopters and only in well-defined contexts. And that's all about the physics that governs their operations.

"I'm not uninformed at all. The only difference between you and I is that you might know a little more math than me."

There's a couple ways of responding to that:

1. I topped out at calculus. But calculus is what you need to really understand orbital mechanics, and not just take other people's word for it. And orbital mechanics is the essential discipline of the physics that you deny has an effect on anything.

2. Reading the wrong stuff -- especially when you don't have the math and engineering horsepower to tell the crap from the facts -- doesn't make you informed. It makes you misinformed.

Science fiction authors write fiction. It doesn't matter which ones you read or how plausible they can make their ideas sound, it's still just fiction. Relying on what you read (in even the hardest SF) in a real world astronautics conversation is not a good idea.

I've already explained this once before: using exclamation points for antything other than interjections is exhortative and rude. Please refrain in the future.

WRT SSTO, no, it's not as fantastic as speculative FTL technology. It's probably just barely possible under the right conditions. But that doesn't make it any more practical in the real world than warp drive, because the real world isn't just about technical possibility, it's about economic practicality as well.

"...as a Navy man, you..."

As already mentioned more than once, I'm a former Marine who happened to spend a lot of time on US Navy ships for one reason or the other.

"In any case, like I said, SSTO is just one of many technologies which I expect to see in the future as companies compete to drive down the cost to get to LEO and beyond."

You can expect anything and everything you want. But that's not going to make it happen.

Also, there's absolutely no incentive to compete on cost with the mature technologies at hand. Launch vehicle manufacturers/operators compete on reliability, because as expensive as the LVs are, the payloads cost a whole lot more, as does the time lost to LV failures.

"My fundamental position is not necessarily "SSTO is practical", but rather..."

Also, there's absolutely no incentive to compete on cost with the mature technologies at hand. Launch vehicle manufacturers/operators compete on reliability, because as expensive as the LVs are, the payloads cost a whole lot more, as does the time lost to LV failures.The price of satellites is significantly influenced by the cost of lift; they could be significantly cheaper if weight were less of a factor. However, as long as there isn't another major space-based application that needs large amounts of space lift, space lift won't get much cheaper, because there simply isn't the demand to justify the research and development costs. It probably wouldn't take anything but mass production to reduce the cost of space lift by a factor of ten.

"The price of satellites is significantly influenced by the cost of lift; they could be significantly cheaper if weight were less of a factor. However, as long as there isn't another major space-based application that needs large amounts of space lift, space lift won't get much cheaper, because there simply isn't the demand to justify the research and development costs. It probably wouldn't take anything but mass production to reduce the cost of space lift by a factor of ten."

You know, that's one of those space advocate articles of faith that has gone too long unexamined. Lowered launch costs are not going to lower the cost of spacecraft significantly, if at all. There's still the space environment to design and build for. No matter how cheaply or how regularly you can launch into space, spacecraft are still going to be rare and expensive. Orbital space is limited as well, especially in the prime geosynchronous positions. There's no use for more and cheaper spacecraft. That means there's no use for more and cheaper launch vehicles, except for exploration, and that in itself, because it involves limited opportunities and/or humans, is never going to be the realm of smaller, cheaper spacecraft.

You know, that's one of those space advocate articles of faith that has gone too long unexamined. Lowered launch costs are not going to lower the cost of spacecraft significantly, if at all.I'm not a 'space advocate', but that's a silly claim. There are all sorts of components (e.g. solar panels) where you can have lightweight but expensive vs heavier and somewhat less expensive. If it costs $2,000 to trim a kilogram of weight, and cost to orbit is $10,000/kg, you trim that kilogram. If cost to orbit is $1,000/kg, you don't. You might not get dramatic changes in weight/cost, but it's not something you can ignore.

I don't think anybody said you were. The argument you offered is, however, one of the staples of space advocacy.

"There are all sorts of components (e.g. solar panels) where you can have lightweight but expensive vs heavier and somewhat less expensive. If it costs $2,000 to trim a kilogram of weight, and cost to orbit is $10,000/kg, you trim that kilogram. If cost to orbit is $1,000/kg, you don't. You might not get dramatic changes in weight/cost, but it's not something you can ignore."

Sorry, but you're engaging in a non sequitur here. No matter how cheap access to space is, the incentive would still be there to squeeze more capability into a given payload mass. IOW, a spacecraft customer told that he could afford to put more mass in space for X millions of dollars wouldn't choose to make cheaper, less efficient spacecraft. He's still only got one GEO orbital slot, and the opportunity cost in the time and resources necessary to replace failed equipment is going to be as big as ever. He's going to build more capability/ redundancy into that extra mass, not less cost.

Even if Tony was wrong on this particular point, you have to consider this: is it easier to optimize the payload utility (or mass) than to optimize launch costs?It seems there are much stronger fundamental constraints for launchers (not thinking in nominal dollars here but relative value) than for payloads. History is a poor guide and all but, short of a space elevator, physics and history seem to be on the same side.

There is, I think, a tendency on the part of some people to regard our launch vehicle technology as immature because it doesn't satisfy their idea of what it should be able to to. And, for some crazy reason, they can't be told that what we have is what we've got. 50 years of experience is nothing in the face of dreams.

No matter how cheap access to space is, the incentive would still be there to squeeze more capability into a given payload mass. IOW, a spacecraft customer told that he could afford to put more mass in space for X millions of dollars wouldn't choose to make cheaper, less efficient spacecraft. He's still only got one GEO orbital slotNon sequitur there. Orbital slots are not mass-limited, and if it doesn't need to go into geostationary orbit aren't even all that limited. What people actually optimize for is (total cost of satellite plus launch cost of satellite), subject to the problem that launch costs are quantized because rockets come in a limited variety of sizes and there's rarely a lot of use for surplus cargo mass on a rocket.

"Non sequitur there. Orbital slots are not mass-limited, and if it doesn't need to go into geostationary orbit aren't even all that limited. What people actually optimize for is (total cost of satellite plus launch cost of satellite), subject to the problem that launch costs are quantized because rockets come in a limited variety of sizes and there's rarely a lot of use for surplus cargo mass on a rocket."

You're missing the point. If you have one orbital slot, howeverm uch mass you're going to put up there is going to optimized, whether the spacecraft is 5 tons or 50. A spacecraft customer, confronted with a bigger mass budget, isn't going to say, "All right, put on the cheaper, heavier solar panels." He's going to say, "How much more routine service power and backup power can I get with the best technology and my increased mass budget? How many more extra and/or redundant goodies can I add?"

And you're wrong that non-GEO orbits are less limited. If you need a pass over a specific lat/long at a certain time every day, then you have a very narrow orbital slot in which to stick your spacecraft. And most LEO applications that I can think of, military or civilian, have this kind of limitation, usually having to do with constellation geometries.

We seem to be talking about different things.You're talking about the first mission while I'm talking about the whole campaign. And you seem to be talking about a different sort of operation.

I see how you could have a stunt where you send people to die on Mars without having done much robotic groundwork, without much equipment to get work done and barely more supplies than they need to reach the place. If you're trying for a stunt, I figure that could be a good bit cheaper than a proper mission.I also figure the cost of productive Moon mission would differ even more relative to a Moon stunt.But you're talking about bringing people back from Mars. How much would you save relative to the mission cost by downscoping it to a stunt?You say mission duration is irrelevant. Does that mean you are assuming a relatively low mass cost for extending life support way beyond the duration of a Moon trip? Or are you envisioning some kind of new propulsion technology that could make Mars a month-long trip or something?Or maybe we have a different definition of "stunt". I'm not sure what you'd expect the follow-up on a successful mission to be.The way I envisioned it, the length of the trip dominates the mission costs (either because of the duration or because you need a huge acceleration) and that factors in basically everything.Which is to say I don't understand why landing and launching would double the mission mass either. I'm not envisionning landing with the deep-space life support "module" for instance, again a decision in part driven by the mission duration.Maybe I'm missing something simple.

With regards to testing, what tests could you do safely on the lightweight Mars orbit trip that you couldn't do on Earth, on Earth orbit, without a live crew or, if that was the only way, in the course of a first complete mission?I don't think there would be a rationale for a manned Apollo 10 today but I don't understand how Mars could be done with that approach anyway. Apollo could afford a ridiculous number of missions due in part to the short mission duration. Mars has different economics.

Moderator: apologies for the previous post. I'll repost it in the right topic.

Longer-lasting sats means lower sat costs for the same service (over the long run anyway).But would it not be more productive to subsidize the development of longer-lasting sats or even standardized serviceable sats and the assorted robots than more efficient launchers?

Its threads like this that make me wonder whether innovation in space is even desirable, as far as cost goes. Things are good enough as they are (Soyuz being the crowning example). Why bother to change things?

Geoffrey: innovation that reduces cost is welcome. This is not necessarily flashy high tech. Much innovation is simplification and optimization. Deciding to design a launcher to minimize cost rather than maximize performance is an innovation that took surprisingly long to gain traction.

Innovation that introduces some valuable new capability is also welcome. But the capability has to really be valuable, not just "pretend valuable".

"Its threads like this that make me wonder whether innovation in space is even desirable, as far as cost goes. Things are good enough as they are (Soyuz being the crowning example). Why bother to change things?"

If there's a significant, economically justified improvement to be made, it will be made. Even our matured liquid fueled rocket technology can be evolved marginally over time. But space flight, particulary launch vehicle technology, is an object lesson that perfect really is the enemy of good enough.

WRT Soyuz in particular, the Russians have proven that when you pick a good design and stick to it, you can get a lot done.

You're missing the point. If you have one orbital slot, howeverm uch mass you're going to put up there is going to optimized, whether the spacecraft is 5 tons or 50. A spacecraft customer, confronted with a bigger mass budget, isn't going to say, "All right, put on the cheaper, heavier solar panels." He's going to say, "How much more routine service power and backup power can I get with the best technology and my increased mass budget? How many more extra and/or redundant goodies can I add?" A routine customer is going to go "this is what I need up there. I can pick launcher model A and launch 1 ton for $10 million, or model B and launch 1.5 tons for $15 million. I know I can fit the capacity I want in 1.5 tons, but will it cost less than $5 million to trim the weight down to 1 ton?" In practice, you have to decide on your launch system before you fully design your payload, so the answer to that question might be hard to determine, but that's the basic economic logic.

"A routine customer is going to go "this is what I need up there. I can pick launcher model A and launch 1 ton for $10 million, or model B and launch 1.5 tons for $15 million. I know I can fit the capacity I want in 1.5 tons, but will it cost less than $5 million to trim the weight down to 1 ton?" In practice, you have to decide on your launch system before you fully design your payload, so the answer to that question might be hard to determine, but that's the basic economic logic."

Even at $10,000 a kilogram, the launch vehicle is a marginal cost. A 5 ton satellite that costs $200M to design and build would cost $50M to launch, for a (very simplistic) total cost of $250M. Slash launch prices in half and the satellite still costs the buyer $225M to put on orbit. The buyer has several options here, but none of them involve radically changing the economics of spacecraft design and construction. The two most likely direction to take decreases in launch cost are in fact to take the same budget and buy a somewhat bigger LV for a somewhat more capable spacecraft, or to just take the savings on the LV and direct it toward profit or some other use.

Geoffrey S H said:"Its threads like this that make me wonder whether innovation in space is even desirable, as far as cost goes. Things are good enough as they are (Soyuz being the crowning example). Why bother to change things?"

It's sad when so many bright people cannot recognize sarcasm when they read it.

"Geoffrey S H said:"Its threads like this that make me wonder whether innovation in space is even desirable, as far as cost goes. Things are good enough as they are (Soyuz being the crowning example). Why bother to change things?"

It's sad when so many bright people cannot recognize sarcasm when they read it."

It's even sadder when an attempt at sarcasm states mostly recognizable fact.

I wasn't being sarcastic- I do occasionally flip between idealist and cynic. No matter what my views about spaceflight, I do however think the Russians should just modernise the equipment for making Soyuz and not try and develop a replacement- its too good a vehicle to abandon right now. it has possibly the best safety record of any vehicle in space , early years notwithstanding and thus should not be replaced by an untried vehicle. Complemented maybe, but not completely replaced.

Because it's not exactly clear that the market really wants to optimize for LV cost. The market is much more concerned with reliability.

Reliability is a third dimension over which to optimize, and it's a dimension that's not really at odds with economy. Vehicles become reliable by being flown a lot, and that's easier to do when the vehicle is less expensive.

In contrast, performance often comes at the cost of extra complexity and lower margins, both of which work in opposition to reliability.

"Reliability is a third dimension over which to optimize, and it's a dimension that's not really at odds with economy. Vehicles become reliable by being flown a lot, and that's easier to do when the vehicle is less expensive.

In contrast, performance often comes at the cost of extra complexity and lower margins, both of which work in opposition to reliability."

In a normal aviation context, I'd agree with you. In a launch vehicle context, reliability is derived from extensive ground testing of components in development and thorough testing of flight hardware before flying it. Flight frequency does not mean all that much because each hardware set is used only once. The repeatability-with-the-same-piece-of-hardware dimension of reliability just doesn't exist. IOW, rockets exist in the round of ammunition reliability regime, not in the transportation vehicle reliability regime. And with rounds of ammunition, service experience can help, but once you're past development and into operations, good design and manufacture are much more important.

That works out to a 96.0% flight success rate. But, significantly, it's 100% for the last 62 flights.

In terms of overall crew safety, it's even better. None have been lost to launch vehicle failure, of which there have been two. 98.5% of crewmembers have been returned safely (TMA-21 and TMA-02M flights are ongoing). Only two crews have been lost to spacecraft failures, both during reentry, for a total of four crewmembers. The last such failure was forty years ago.

I don't think the ammunition analogy quite holds up either. Most ammo rounds are made in large numbers by true mass production, and firing them off is a pretty simple process.

In space launches, the firing-off process is the biggest part of the whole process (said to be ~70 percent of launch cost). I'd guess that working with familiar equipment - both reusable ground facilities and the expendable booster itself - is a big leg up for the launch team.

It might be best to think of the launch itself as a manufactured product.

"I don't think the ammunition analogy quite holds up either. Most ammo rounds are made in large numbers by true mass production, and firing them off is a pretty simple process.

In space launches, the firing-off process is the biggest part of the whole process (said to be ~70 percent of launch cost). I'd guess that working with familiar equipment - both reusable ground facilities and the expendable booster itself - is a big leg up for the launch team.

It might be best to think of the launch itself as a manufactured product."

I think the industry has the terminology right -- a lunch is a service (WRT the spacecraft owner-operator). The launch vehicle is a consumable item used in the provision of that service. But, as services go, it's not like a restaurant meal or a pleasure cruise. In those types of services, everything that goes on under the hood is pretty opaque to the buyer. In the case of launch services, a lot is transparent, and has to be. It's a very collaborative process.

In any case, I think round of ammunition is still a relevant paradigm for the hardware portion of the service delivery. Like ammunition, the working out of kinks is front end loaded to the development and testing stage. Once the final certification flight has been completed, just like a bullet or an anti-tank rocket, the LV hardware is expected to work every time.

That works out to a 96.0% flight success rate. But, significantly, it's 100% for the last 62 flights.Sadly, a run of 62 successes is not particularly strong evidence for much; it's 95% chance that the actual failure rate is less than 4.7% and a 90% chance that it's less than 3.6%. Given that it did have prior failures, I suspect the 'mature' failure rate is still probably in the 1-3% range and they've just been modestly lucky. For comparison, the STS had a run of 110 consecutive successful launches and 81 consecutive successful missions (Columbia failed on re-entry, not launch).

In general you expect later missions with a given bit of hardware to be more reliable, because every time something goes wrong you go back and try to fix it. Unfortunately, this process isn't very fast, it's probably something like halving the failure rate for every ten-fold increase in launches.

"Sadly, a run of 62 successes is not particularly strong evidence for much; it's 95% chance that the actual failure rate is less than 4.7% and a 90% chance that it's less than 3.6%. Given that it did have prior failures, I suspect the 'mature' failure rate is still probably in the 1-3% range and they've just been modestly lucky. For comparison, the STS had a run of 110 consecutive successful launches and 81 consecutive successful missions (Columbia failed on re-entry, not launch).

In general you expect later missions with a given bit of hardware to be more reliable, because every time something goes wrong you go back and try to fix it. Unfortunately, this process isn't very fast, it's probably something like halving the failure rate for every ten-fold increase in launches."

You're applying statistical methods incorrectly. Each launch is not an independent statistical event. It is directly affected by experience gained on all prior launches. As you yourself said, noted anomalies (the vast majority of which do not cause mission failures) are addressed in future hardware and procedures. So the reliability of the system goes up with each flight in which fixes are implemented. It doesn't stay the same.

Notable in this respect are the Challenger and Columbia. They were both* caused by noted performance anomalies that were accepted as "normal" rather than investigated and remediated.

*Columbia's last flight was far from the first time that foam had come off the ET and struck an orbiter's thermal protection system.

WRT what constitutes a launch vehicle failure, the loss of Columbia was indeed the result of poor launch vehicle design and execution. While thermal protection system failure was the proximate cause of the vehicle loss, the root cause was foam detaching from the ET and striking the orbiter. The ET was an LV component that should have been designed with that class of failure in mind and, after all of the previous experience with orbiter foam strikes, should have been redesigned and executed with that failure mode in mind.

IOW, the failure of the thermal protection system, in the way that it did fail, would never have had a chance to happen if the ET wasn't dropping crud on the orbiter during ascent. And after it was known to be dropping crud on the orbiter and damaging thermal protection system components (tiles), there was a second opportunity to review the problem and remediate it.

One of my favorite shows is on the History Channel's "Modern Marvels", their Engineering Disasters episodes. Each of these disasters occur because of several layers of failure; both Shuttles' crashes are prime examples of this.Political goals influence management decisions that override engineering practices leading to safety concerns being ignored ultimately resulting in the unnescisary loss of a spacecraft and crew.

"I wonder on the "cost" arguments. Why must we assume the current economic model for the Plausible Mid Future?

Our current economic model is constrained by politics, not Resource driven reality. Its possible that might at some point change."

The juxtaposition between politics and resources doesn't exist in reality. Resources are allocated by markets. Politics are simply the specific market in which publicly expended resources are allocated. As long as manned spaceflight is a publicly funded endeavor, politics will govern how many resources are allocated to it, and in what ways. And, AFAWCT, governments will be the only steady customers for manned spaceflight far into the midfuture.

For example in the US we have the resources to solve our current and projected future Energy Demands without using oil. However we chose not to use them for this purpose."

No disrespect intended, but the above is pure ideology. Whatever we have the resources to do or not do, until the markets find them cheaper than petroleum, we will use petroleum. Likewise, whether or not we could theoretically build and launch 10, 100, or 1,000 manned rockets a year, the marketplace of ideas in Washington will decide what NASA buys, not any ideological vision.

Oil isn't cheaper than Nuclear Power unless you include the current political realities."

The current political realities inform market decisions but they aren't the only realities that inform the market. Market value is not a fiction, except in highly technical discussion of market mechanics. In practice it's a reality created from the consensus of all of the market participants and stakeholders. They decide what something is worth. And the market has decided that nuclear power isn't worth all of the risks involved.

"Gasoline cars aren't cheaper than electric cars for any engineering reason. They are only cheaper because we make so many of them."

And we make so many of them because electric cars don't perform like gasoline cars, particularly in terms of range and dispatch reliability.*

*A four hour charge to go 200 miles? Really?

"From a resource standpoint oil is more "expensive" than Nuclear Power."

Not right now it isn't.

"It is also more "expensive" than Solar or Wind."

Once again, not right now it isn't. Also, solar and wind have not conclusively demonstrated positive energy output for resources invested.

"Once you add in all the resource intensive costs of projecting military force to ensure you can get the oil, oil becomes the most "expensive" form of energy on the planet. From a resources standpoint."

Not even close. Domestic pitchblende isn't unlimited. Eventually we'll be making military expenditures to ensure overseas fissionables supplies. If we go to solar? We'll have military expenditures to secure copper and gallium. Wind? Domestic iron and aluminum aren't unlimited either.

"Its the same for any other Market "Reality".

Do you think we (as a planet) are letting all those people starve in Africa because we can't "afford" to feed them?

No, we chose not to."

We choose not to because there's no profit in it and the political market doesn't have enough participants that care enough to make it a public expenditure. Those are the market realities.

"Keep in mind your adherence to this Market Driven concept is also just "ideology".

Money is an artifical construct that amounts to the expression of political will.

The "Market" is just an extention of politics."

The market is a human evolutionary adaptation to limited resources. The shape of any particular market has political, social, and technical dimensions. But the market itself always exists. That's Econ 101 stuff, Phil.

The Econ 101 stuff you mention is merely describing how things exist in our system as it has developed.

Even if the system were to continue pretty much like it has into the plausible mid-future there is no reason to suspect the current policies will also continue.

============================

None of the rest of that are actual resource driven realities. They are political ramifications.

----The Electric car's limited range? A problem because of the political reality that we think 50+ mile comutes make sense in America.

-----The cost of a Nuclear Power Plant? More than 50% of it is poltically related. How many half prioed Nuclear Power Plants could you buy for what we spent on the Iraq War+$100/barrel oil+ Military presense in the Mid East+ the cost of everything else related to oil production?

The fuel for a Nuclear plant is a total non issue, it is a decimal point compared to the cost of the Plant.

You can go to a Plutonium or Thorium economy to help supply .. Both change the equation drastically.

----Resources for the Solar and Wind? Nice little contrarian strawman trick you played there. You say you can't get away from current money realities and then use a different money reality as an argument against the idea. You also assume the technology. For example you can make a solar panel with no copper at all.

===========And finally "the market" is not a human evolutionary anything.

Human evolution is biology.

The Market is a social construct. It is a product of civilization, not evolution. It only exists in the confines we establish.

Money was invented long before governments had evolved much beyond warlordism. Money is a quick and convenient way of trading value; ancient Cypriots cast their copper ingots in the shape of stylized ox hides, and most of the "civilized" world of the Bronze age accepted that one ingot of Cypriot copper was indeed worth one Ox in Hatti, Mycenae or Egypt and beyond. This value was not set by governments or central banks, but by common agreement among traders.

Fiat money acts in much the same way despite the protestations of various governments or central banks. Canadian dollars have traded between .60 USD to currently 1.04 USD over the last two decades. In Canada, a dollar still buys a dollar's worth of goods, because Canadians generally agree on the value, but things look a lot different when going on vacation or purchasing goods and services outside of Canada. These fluctuations are not caused by our government directly, but by traders comparing values and government policy (the $Cdn was worth .60 in the 1990's when we were facing our debt crisis, a rude awakening to the then current government by the worlds financial markets).

Markets themselves exist as a sort of ecosystem of information exchange. Transparent and efficient markets allow information to flow freely, allowing exchanges of value to occur without any party feeling cheated. Inefficient markets generally have information bottlenecks (sometimes deliberate ones imposed by governments or oligarchies seeking advantage), and so are less effective or efficient in attracting resources to areas where they can create the greatest value.

IMO you both fail economics in this exchange (Tony and Phil, though Phil more so.) The cost of space access isn't political, but reflects the extreme resources needed to get up there and have a working or safe payload out there. One governments vs. another might choose to throw more resources at the problem, but the $3-10K/kg cost reflects the resources actually needed.

It is true that oil (and coal etc.) may well be more expensive than nuclear and solar etc. when all costs (global warming and other environmental damages, building our infrastructure around such a limited resource) are factored in, and that's something politics can adjust (pollution tax, excise tax for taking it out of the ground in the first place).

Electric cars suck because batteries suck, especially in energy density. Cars run by burning C and H, lightweight elements, in a free O2 atmosphere, meaning 36/50 of the total fuel isn't even carried onboard. Batteries involve heavier elements and carry all their oxidizer with them. And they're expensive because lithium is rare and stuff.

Of courses, it was a political decision to allow us to build up around cars so much, vs. electrified public transit.

Suggesting we'd have to go to war to secure access to iron and aluminum the way we do for oil seems like a really desperate attempt at equivalence-making. Fe and Al are as common as dirt.

I've seen EROEI of 10 for solar and 18 for wind. That's pretty positive. Not as positive as the 100 for oil in its heyday, of course, and there's the storage problems of getting all of our power from solar/wind.

I lean toward Damien S. in this economics discussion. But no one is likely to persuade anyone, given that economic views tend to be held with quasi religious intensity. (A remarkable phenomenon, if you think about it.)

That said, space travel is inherently difficult. Lean, mean organizations might achieve it at half or a third the cost of bloated organizations, but that makes a pretty modest dent in costs that are on order of 1000 times those of intercontinental air travel.

IMO you both fail economics in this exchange (Tony and Phil, though Phil more so.) The cost of space access isn't political, but reflects the extreme resources needed to get up there and have a working or safe payload out there.===============

You are entitled to your opinion of course -- but .. what are the extreme resources?

We could perhaps list them?

Human resources? Do we not spend many many times the amount human resources developing consumer products?

The technology? Again we spend tons of resources developing "technology" now. By comparison Space Development is a tiny fraction.

The Metals? Polymers? Rubber? Plastics? Electronics? Ceramics? (whatever) Spacecraft use a relatively small amount. Compared to say a year's production of cars.

I don't think the "extreme" resources actually drive the current cost of space travel/ Satellites/ Whatever. I think the "extreme" specialization does.

By way of example -- I worked on a pretty aggressive development program about 10 years ago.

New Engine, New Control System, New Chassis, etc.

Everything cost a ton of money because it was "the first" or "the tenth" of something.

An engine would cost $450,000 or a Starter $11,000. A processor might be $5000

But that wasn't the cost things ended up at. A few years later the engines cost ~$10000, and the Starters ~$500. Processors ~$200. And we still had not built more than a hundred of them.

In the plausible Midfuture .. say 300 years from now. They might be working on a heavy lifter that was developed 50 years prior. They might have built hundreds or thousands of them. That lifter is not going to "cost" anything remotely similar to the cost a lifter does now.

The weather satellite they are sending up might be Serial number 211 developed 20 years before. That satellite isn't going to "cost" what a satellite does now.

That Jupiter exploration vehicle might be using a spaceframe, reactor and drive design that were all developed over 100 years prior. There may have been dozens built before to do other explorations. In fact it probably shares a platform with a lot of other space vehicles. It isn't going to be Apollo all over again.

Not that Apollo was all that expensive a development project. ~170 billion in 2005 dollars according to Wiki. We spent a lot more on defense development during those years.

The reason electric cars are a non starter today is the same reason that electric cars were doomed in the early 1900's (when electric cars actually outnumbered gasoline and steam powered cars); the lack of the electrical infrastructure needed to charge large fleets of cars. It was far cheaper and quicker to build an infrastructure to transport and sell liquid fuel.

Today, it only takes a modest solar panel on the roof to power a house, but the amount of solar panels needed to power a car would be improbably large. The energy cost of moving mass around is far greater than powering a household full of appliances.

The current infrastructure of electric generators and transmission lines is nowhere near capable of powering a fleet of replacement electric vehicles.

As for resources; they are attracted through the market to projects wich promise a return on investment in a reasonable timeframe. Mot investors are impatient for the next quarter's earning statement, how will they wait twenty years for a result? Perhaps a Bill Gates or Apple Corp could afford to fund a foundation or think tank for long term projects with 5-30 year horizons, but few others can. To ask governments to do so is utterly unrealistic. Politician's time horizon is the next election and bureaucrats time horizon is the next budget, only slightly longer than the time horizon of an investor. This is even discounting the current overleveraging crisis of the world's governments.

We spend more on consumer goods, yes. We also get far more consumer goods out of that spending. $1 billion gives a loaf of bread or bag of rice or cheap burger to 300 million Americans... or lifts 7 people into LEO on the Shuttle. Being expensive doesn't just mean total amount, but bang for buck. And apart from satellites and research, space offers about zilch bang for very many bucks.

I don't know enough to say mass production wouldn't bring costs down a lot, but the problem is that even if you reduce launch and building costs by a factor of ten, there's still little obvious market. $300/kg to LEO would still reserve space tourism to very well-off individuals, or the somewhat well-off who saved like mad and splurged. Don't know what it'd do for satellite solar power.

IMO you both fail economics in this exchange (Tony and Phil, though Phil more so.)"

Actually, I got an "A", graded by a former oil industry analyst who might have known just a little something about the subject.

"The cost of space access isn't political, but reflects the extreme resources needed to get up there and have a working or safe payload out there. One governments vs. another might choose to throw more resources at the problem, but the $3-10K/kg cost reflects the resources actually needed."

And? Of course the costs aren't decided by politics. Whether or not money is allocated to pay those costs is. And that is a market process. The political institution is presented with an aray of things to spend money on, is subjected to various suasions, and decides to buy X amount of this, Y amount of that, and Z amount of the other thing. It's just like a trip to the supermarket, in fundamental terms.

The form of money is not entirely irrelevant. Fiat money has the advantage of being readily transferable and convertible. It would be hard to imagine a technological society using barter or even hard currency for most transactions.

"It is true that oil (and coal etc.) may well be more expensive than nuclear and solar etc. when all costs (global warming and other environmental damages, building our infrastructure around such a limited resource) are factored in, and that's something politics can adjust (pollution tax, excise tax for taking it out of the ground in the first place)."

Except that political adjustment is usually very inefficient, because it's based on ideology, not practical knowledge. The market works better. As petroleum becomes rarer and more expensive, other sources of energy will appear more practical to the market than they do today. Then the market will buy them.

"Of courses, it was a political decision to allow us to build up around cars so much, vs. electrified public transit."

Actually, electrified public transit was deprecated in favor of motorized buses. There was definitely an industry-political axis that moved that along, but private cars were an entirely different dimension of the transport industry. Private vehicles became popular because they symbolized success and independence. No amount of public transport, no matter how equipped or configured, could compete with that.

"Suggesting we'd have to go to war to secure access to iron and aluminum the way we do for oil seems like a really desperate attempt at equivalence-making. Fe and Al are as common as dirt."

Yes, they are as common as dirt. I can literally walk outside from where I'm sitting right now and run my fingers through soil containing both. But workable deposits of hematite and bauxite? Not so much. There's nothing "desperate" in recognizing that.

"I've seen EROEI of 10 for solar and 18 for wind. That's pretty positive. Not as positive as the 100 for oil in its heyday, of course, and there's the storage problems of getting all of our power from solar/wind."

So have I. That doesn't mean that I unconditionally believe it. If we're going to deprecate oil on the environmental and other extended costs, then we have to so the same for solar and wind (both of which have environmental impacts).

"To ask governments to [engage in long term projects] is utterly unrealistic."

Governments do so all of the time. The payoff just has to be big enough. National defense, for example, involves maintaining and equipping the military/naval/air institution -- a project of indefinite duration. But the payoff is pretty obvious and pretty obviously worth the expense and commitment. For stuff like the ISS -- or a steady manned space program of any type -- the payoff is calculated in science return and national prestige. Governments do invest int those things over the long term, as the ISS itself demonstrates.

Except that political adjustment is usually very inefficient, because it's based on ideology, not practical knowledge. The market works better. As petroleum becomes rarer and more expensive, other sources of energy will appear more practical to the market than they do today. Then the market will buy them.

==================There is no way to separate "the Market" and "Political Adjustment"

They are literally linked at the hip.

The conditions of the market are determined by political conditions.

They always have been.

==========The "A" comment made me laugh. I also got A's in my economics classes. Not to mention Poli Sci and History Classes. It doesn't mean that either of us is getting our point across though. Nor do any particular grades make either person "right"

I would agree that politics help create the environment in which the commercial market operates. But the political market in which public funds are allocated is an entirely different animal.

"The 'A' comment made me laugh. I also got A's in my economics classes. Not to mention Poli Sci and History Classes. It doesn't mean that either of us is getting our point across though. Nor do any particular grades make either person 'right'"

I'm glad I could provide you some amusement. Strangely enough, I'm not seeking to be "right". I'm just offering my opinion. I'm perfectly sanguine to let the readers decide which, of all the opinions offered, is convincing.

"But the commercial "private" market is also completely permeated by political affects.

All the prices are swayed by political entities of one level or another."

So? Political institutions don't create the market. The market exists simply because people find trade less of a hassle than robbery, most of the time. Politics just hems it in and pulls it this way and that. But it's there because it's a necessary function, not because politics makes it so.

"There is also no real difference between public and private funds. All the money comes from the public sector originally.

It is basic fiat currency accounting:

*The Government spends money by creating it out of thin air...

*The "Private Sector" competes over the money, in the process it changes hands many times ...

*The "Private Sector" pays its "taxes" to the government..

*The government then destroys that money.

(rinse, repeat)

How can the market be separated from the public sector in that system?"

The government supplies a monetary system and guarantees (to the degree that it can) its reliability. But without governments, monetary systems woud exist. In many places today, for example, US $100 bills are the defacto monetary system for large transactions because government money is just not stable, while US currency is respected everywhere. (Yes, still, even after all of the trouble we've had with our money recently.) Or, to being it closer to home, I can remember running into Europeans and Australians overseas, who would go on vacation with a wad of $100 bills, because the combined premium paid on buying and selling dollars was still less than converting their own currencies outside of their countries. And if you've been watching hte news, you know what gold and silver are worth, wherever you go.

Which is all going the long way 'round the barn to say that money is whatever portable goods people will take in exchange for products or services. How it's value is derived, whether from wealthy and reliable backers (fiat monies of powerful states) or from inherent material value (platinum/gold/silver/whatever) doesn't change that.

Money was independent of governments for most of its existence, our current situation of an all fiat money economy dates back to 1973, which makes it slightly younger than the Moon landing.

Tony is correct in money having value because people believe in it; my wife and I went to Jamaica once for a family visit and were rather astonished to discover that our decision to purchase Jamaican currency was unwelcome there (they were expecting USD for cash transactions like purchasing drinks, cab fare or tips).

Still, money is a shorthand for the time and resources you have available, so some form of currency is going to be around for a long time to come. An interesting concept is Purchasing power parity (PPP), the Economist used to run a feature which compared the price of a MacDonald's meal in various nations in their own currency, which was a good gauge of what the currency was really worth. (Other PPP examples I remember was the price of a beer, which was also quite interesting when compared to the price of the same brands that were available here in Ontario....)

Someone with access to reliable information might compare the PPP of a kilogram to orbit delivered by various launch systems on the market today.

"Except that political adjustment is usually very inefficient, because it's based on ideology, not practical knowledge. The market works better."

An ideological statement itself. The market does not work at all at accounting for many kinds of costs, particular pollution ones. "Externalities". Thus environmental regulations, cap and trade, pollution taxes. The market did not reduce CFCs and acid rain and clean up rivers.

"As petroleum becomes rarer and more expensive, other sources of energy will appear more practical to the market than they do today"

Yes, but if governments were raising the prices to fully account for costs, alternative energy would look more practical right now. As is the case in Europe, where for what ever reason gasoline taxes have generally been in the dollars per gallon range rather than tens of cents per gallon range.

"Private vehicles became popular because they symbolized success and independence. No amount of public transport, no matter how equipped or configured, could compete with that."

Private vehicles and lifestyles centered around them also received huge subsidies in roads and home mortgage subsidies. And public transport, including electrified rail, is much healthier outside the US.

"Money was independent of governments for most of its existence"

Ehhh sort of. Money wasn't explicitly fiat money. But coinage often shifted from "we certify this has X silver in it" to "please take this coin to be the same value as the previous coin, even though we're now making it with less silver". And I think China had paper money like 1000 years ago, which is a big chunk of the history of money.

"resources =/= money"

Money represents resources (including labor), and can be exchanged for them. Government can print new money, but this tends to reduce how many resources can be gotten for a fixed quantity of money. Absent such shenanigans they're not exactly the same but they're pretty connected, and in particular worldwide launch costs can be taken as meaning something real.

Geoffrey S H - I did get your email, and tagged it; I'm just running behind.

As for all the free market hype, let's get real. (Yes, I can get crabby on my own blog.) In that real world, the choice is not between a flea market fantasy of markets on the one hand versus Five Year Plans on the other.

Basically, markets are very efficient at exploiting - in both positive and negative senses of that word - such public investments as ports; roads and bridges; courts of law, grants of public land to railroads, large Boeing jets; the Interstate Highway System; the Internet; and quite a few launch pads, active and 'expended,' in Florida and California. And for that matter the Federal Reserve system.

There is no particular reason to think that it will be any different in space. It most certainly has not been different so far. The space launch industry always has been and remains deeply entangled with policy and politics.

I think what you're missing in asserting that government accounts for extended costs better than markets is that governments are much more subject to ideological suasions than markets. And that's not an ideological statement -- markets are tugged this way and that by the ideologies of individual participants, but a government can make huge investments and disinvestments based on the ideologies of the party in power. And the party in power is most often decided by a few percent of the voters.

Cypriot traders were not told by some government agency that one ingot of copper was worth one Ox, nor did the Hittites or Egyptians have some sort of central agency to enforce this. Money was developed by traders and for traders, and governments stepped in when they realized it was simpler and more effective to seize money rather than real goods (although the relationship between money and real goods continued, for example Japanese wealth was calculated in terms of baskets of rice).

Evn into the recent past, money was often issued in parallel to governments, Canadian Banks issued their own currency right up until 1944, for example, and "Bank" money was backed by the real assets of the banks that issued it. Obviously any bank which made poor choices in their loans portfolio (which is the asset of the bank) would have a hard time having their currency accepted, a rather neat way of self regulating the amount of currency in the economy and a useful damper to prevent inflation. Of course the central banks could and did inflate currency in order to carry out the war effort...

Markets do direct resources efficiently, but are subject to many influences. My model of an economy is an ecosystem, so extraneous influences like political manipulation or the activity of would be oligarchies can and do affect how the markets operate. Free markets operate more effectively and provide more resources. Compare how the relatively free market economy of ancient Greece allowed the Greeks to prevail over the far larger, richer and more populous Persian Empire. The relatively free market of Venice allowed it to compete on nearly equal terms with the larger, richer and more populous Ottoman Empire. The relatively free Elizabethan markets allowed England to successfully compete with the far richer, larger and more populous Spanish Empire in a global confrontation.

In each example, the smaller parties could access their resources fare more quickly and allocate them far better than their lumbering opponents.

"I think what you're missing in asserting that government accounts for extended costs better than markets is that governments are much more subject to ideological suasions than markets"

Yes, but what you're skipping past is that markets have *no way whatsoever* of accounting for external costs. You're comparing a flawed mechanism -- but one that *has* reduced acid rain, CFCs, and other pollution -- with no mechanism whatsoever.

Free markets explained Greek superiority over the Persians? I thought it was military superiority, phalanxes and perhaps a type of nationalism for military morale.

England vs. Spain... Spain is physically bigger, but drier; it doesn't necessarily have more people at any time. Spain had also driven out its Jewish and Moorish middle class, and then suffered inflationary false wealth from American silver; calling all that a lack of free market seems rather simplistic.

"Yes, but what you're skipping past is that markets have *no way whatsoever* of accounting for external costs. You're comparing a flawed mechanism -- but one that *has* reduced acid rain, CFCs, and other pollution -- with no mechanism whatsoever."

You're engaging in confirmation bias here, Damien. Government regulation has also been responsible for ridiculous market distortions like the Great Leap Forward.

"Free markets explained Greek superiority over the Persians?...

England vs. Spain..."

You've got the wrong guy if you think I'm going to give markets credit for anything other than allocating resources within an economic system. Having said that, it's interesting that your examples demonstrate the effect of economic conditions on what governments can do and ultimately achieve.

"Middling orders of society" is probably the better term, and there were many other "middling orders" around- the Spanish mercantile empire was very much in existence, if not as large as it could have been. I wouldn't attribute too much to the expulsions under Isabella.

The system as I have described it is consistent with Modern Monetary Theory (Mosler, Mitchell, etc), Which I have brought up since it basically argues that utilization of available resources is entirely a function of the availability of money in an economy. And therefore whatever your current level of utilization is directly traceable to who controls how much money is in the system. In an economy with a Fiat currency and Currency sovereignty that control belongs to the government.

I brought this up to counter the claim that our utilization of resources for the Space Industry is somehow fixed and tied directly and irrevocably to “The market”. However I argue instead that both the utilization of said resources and that market are both arbitrary, and the realities of both subject to dramatic change.

---------------------------A significant example of this could be the US economy during World War 2. With the utilization of resources paramount, the use of most resources in the country changed dramatically. Far more materiel was produced than ever could be explained by “market forces” Essentially – the government needed a certain resource utilization level and it got it.

I do not see how, in the early oil example, someone could continue to suggest the price of Oil is truly determined by a public sector “Market”. When everything from supply, to distribution to Usage is dependent on political considerations.

I also do not see how a Space Industry steals bread from anyone. Unless perhaps the aluminum used for a particular space craft was needed for some combine used to harvest wheat. Or there was such a shortage of Truck Drivers that the bread truck had to forgo a driver in favor of the rocket fuel truck driver.

"The system as I have described it is consistent with Modern Monetary Theory...

I brought this up to counter the claim that our utilization of resources for the Space Industry is somehow fixed and tied directly and irrevocably to “The market”."

Apparently you are under a misapprehension about what most people mean when they discuss markets. Markets are not specific places or institutions. Markets are simply those spaces in which people negotiate the allocation of resources. The US Congress, the Russian Duma, the Politburo of the CPC -- all are spaces in which the allocation of resources are negotiated. In that respect they are all markets and subject to market dynamics.

"However I argue instead that both the utilization of said resources and that market are both arbitrary, and the realities of both subject to dramatic change."

Arbitrary, huh? People have to be fed, watered and clothed; power has to be produced; resources have to be extracted, refined, and distributed. Those things aren't arbitrary. If governments get to treatingthem like they are, well, then you have this phenomenon called revolution, which is the market solution to fiat market distortion.

"A significant example of this could be the US economy during World War 2..."

It's a very poor example for your purposes. The change in the economy from consumerism to defense production was a reaction to a perceived existential threat, not an arbitrary choice.

"I do not see how, in the early oil example, someone could continue to suggest the price of Oil is truly determined by a public sector “Market”. When everything from supply, to distribution to Usage is dependent on political considerations."

The problem with this assertion is that it overestimates the influence of politics on markets. Political considerations do in fact influence markets, but the existence of the market is a fundamental fact, because there are resources to be allocated and uses for those resources, while the political influences on the market are mere constraints.

"I also do not see how a Space Industry steals bread from anyone. Unless perhaps the aluminum used for a particular space craft was needed for some combine used to harvest wheat. Or there was such a shortage of Truck Drivers that the bread truck had to forgo a driver in favor of the rocket fuel truck driver."

You just answered your own question -- money spent on space isn't spent on other things. Maybe it doesn't directly affect anybody's nutritional security, but it is a choice to do one thing rather than another with the available resources, which does affect what people do and have in the sector that gets deprecated by the choice.

"My point instead is to argue that how we use resources *can*, and most likely *will* change in the Plausible Mid Future."

That's not an argument, that's an assertion. And it's also a tautology -- of course resource allocation will be different in some future year than today. We have enough historical evidence to place that beyond argument.

But your assertion that one of the changes will be toward a much greater level of soace investment is entirely unsupported by anything you've said. Of course nothing that is possible can be summarily ruled out, but we've got a long and consistent track record WRT what both commercial markets and governments are actually willing to invest in space. Barring major and unpredictable changes in priorities, it's simply not likely to change by much.

"If you have resources that aren't being utilized because there is a shortage of money .. create more."

That's a very short term solution. Pretty soon -- like about next week -- you get inflation. Create all the money you want, the market will quickly reallocate the money supply to the supply of resources.

That's a very short term solution. Pretty soon -- like about next week -- you get inflation. Create all the money you want, the market will quickly reallocate the money supply to the supply of resources.

============

As I said *if you have resources that you aren't utilizing* because you lack money...

Then create more money.

You are assuming the market guarantees some maximum utilization of resources. It doesn't.

You wont get any inflation until demand goes up. Which is what you want anyway if you are trying to increase resource utilization.

You dont get uncontrolled inflation until the money grows beyond supply. (Availible resources)

"As I said *if you have resources that you aren't utilizing* because you lack money...

Then create more money.

You are assuming the market guarantees some maximum utilization of resources. It doesn't.

You wont get any inflation until demand goes up. Which is what you want anyway if you are trying to increase resource utilization.

You dont get uncontrolled inflation until the money grows beyond supply. (Availible resources)"

Actually, what I'm assuming is that the market optimizes utilization of human effort over a statistically significant period of time. Underutilization is a temporary condition, just like overutilization is. To bring things back to the topic, manned spaceflight, as a project, is a very long term endeavor. Throwing money at it over the short term isn't going to get you anywhere, and you can't just throw money at it over the long term because the market is not going to tolerate it without commensurate profits. IOW, your Great Space Leap Forward would be just like any other government fiat program doomed to failure by misallignment with economic reality.

"There is no Greap Space Leap Forward- There is utilization of resources.

If you have unutilized resources you could use on Space and you want to use them on Space then you can.

Just like we utilize resources on Defense, or Education, or The War on Drugs, or Baseball, or Reality Television or whatever."

I chose my terminology very carefully, Phil. One can't just utilize unutilized resources because they exist. One has to have the manpower to make use of them. When one doesn't have the manpower -- or when one has improperly skilled manpower, which is also a function of resource allocation -- then trying to get to unused resources causes other sectors to go wanting.

"The market never optimizes anything. And it is never seperate of the political system. The "free" market is a myth."

I really don't GAS about the "'free' market". To me the market is just the market, and politics is just a constraint.

WRT what the market optimizes, what exactly do we think the market actually trades in? Allocation of resources, right? Yes. But market efficiency is a function of how those resources are matched up to people who can use them. When the market is down, it's not resources that are being underutilized. It's people. When the market is heated up and bubble is about to burst, it's not resources that are being overutilized. It's people. When you look at the market over a long enough duration to smooth out these fluctuations, you find that the market optimizes the use of human time and skill towards some goal or goals accepted as worthwhile by the market participants as a community.

"As I mentioned before, Money is just an extention of political will. If you are keeping score yourself and you lose, it is your own fault."

Money is shorthand for human effort. It's just portable and convertible tokens that make transaction easier.

One has to have the manpower to make use of them. When one doesn't have the manpower -- or when one has improperly skilled manpower, which is also a function of resource allocation -- then trying to get to unused resources causes other sectors to go wanting.

=================

But you can!

Manpower is also a resource. If you lack manpower, you lack resources. Hard to utilize resources you lack.

However manpower is a resource you can develop. (IE Educate)

And with the horrendous global unemployment (much much worse tha US levels, let alone historical US levels) ---

I suggest manpower is probably the biggest unutilized resoource we have.

Manpower is also a resource. If you lack manpower, you lack resources. Hard to utilize resources you lack.

However manpower is a resource you can develop. (IE Educate)

And with the horrendous global unemployment (much much worse tha US levels, let alone historical US levels) ---

I suggest manpower is probably the biggest unutilized resoource we have."

Improving the capability -- and thus the economic efficiency -- of manpower involves the allocation of human and material resources that could be doing something else. As previously mentioned, just because a resource exists doesn't mean it is practically exploitable.

Also, improved capability includes expanded outlook. You may have more people doing more valuable work, but they expect more from it -- more food, more clothes, a bigger car (or a car at all), etc.

And you've got to give them something to do. What will they do? Provide themselves more food, more clothes, a bigger car (or a car at all), etc.

Educate and equip all the underutilized people on the planet, then proclaim: "Now, all you minions whose life I have improved...off to Space!!!" They'll reply, "Not at the expense of my food, clothes, car, etc., you wont!"

"They were all unemployed due to a lack of demand in the first place."

If we're talking about the whole world, most people are pretty much overemployed (by Western standards) just trying to survive. The problem is that nobody thinks it worthwhile to allocate the resources to improving their economic efficiency. And while it may be a harsh judgment, it is also true -- given the demands on material resources that a more educated and affluent world would make, it is probably not in your or my best interest to make that happen.

And before you say that exploiting space resources would solve that, no, it wouldn't. It would never get to that point. It's easier and much, much cheaper just to kill your competitors on Earth and take their stuff on Earth.

"Ah - but you missed the point.

If you develop those resources they will increase the demand on other resources (a house a car, etc) -

A demand other aspects of the economy can fill.

Improving the overall economy.

If you then with your new economic engine want to use some of your resources for Space Development -- you are in a much better position."

And while it may be a harsh judgment, it is also true -- given the demands on material resources that a more educated and affluent world would make, it is probably not in your or my best interest to make that happen.

=================

You probably have summed up right here why we don't fix any economy - including that of the current US - in this statement.

"You probably have summed up right here why we don't fix any economy - including that of the current US - in this statement.

'Let them eat cake'"

Considering what happened to France after Louis and Marie got abbreviated, I think she probably had a point -- the country started out rebelling over bread, wound up starting wars to pay for cake, and eventually succumbed to foreign conquest and the reinstatement of the Bourbon monarchy. You're advocating the same kind of something for nothing logic.

Remember - in revolutionary France there was no Cake for them to eat."

So they went elsewhere to steal cake, because they coudn't make it by an act of will.

Likewise, you can't lift up the massess by an act of will. And if you invest the resources to lift up the masses, you then have to provide the resources for them to live uplifted lives. Except there probably isn't enough to go around for every one of billions of humans to live even the lifestyle of poor Westerners, no matter how well educated everyone is.

Going back to the historical examples for a moment, while it is true that Greek military science and cultural cohesion were important factors in winning the Persian wars, the Greeks had to cough up the resources to feed, arm and equip all these men from a relatively poor agrarian society.

If the Classical Greek economy worked anything like the Persian one (where most things happened by the fiat of the Great King or his lesser minions), then the advancing Persian Army would have been met with (at best) tiny fully equipped royal bodyguards and perhaps a larger number of "peasant levies" firing sling stones. Indeed, if the Persians had invaded Greece a few hundred years earlier, that is exactly what would have happened, the Mycenean "Palace" culture could only produce that sort of military force.

Similarly, the Elizabethan economy was far smaller than Spain's at the time, Phillip could call on the resources of Spain, many Habsburg allies and buy the services of many others across Europe. Elizabeth Gloriana was broke, and could only meet the challenge through offering incentives to pirates (er, Gentlemen of Fortune) to attack Spains source of wealth in return for a cut of the loot. The actual contributions on land (in the United Provinces) tended to be small and poorly equipped, as there was never enough loot to pay for an army, and piracy offered a far better rate of return in both monetary and military terms.

Phil, you're right that one can print money to mobilize unused labor. That's what Keynesianism is all about.

Problem (relevant to this site) is, having mobilized the labor and resources, what do you pay them to do? Yes, you could have them do space stuff, at little cost relative to the depressed economy... but the relevant measure is opportunity cost: you could have them building high speed rail or cleaning up pollution sites or rebuilding infrastructure instead.

Money isn't resources? Yeah, sure. Problem is, there aren't any space resources you can get for less investment of resources than you could get by terrestrial means, by current valuations. Money's a shorthand for all of that.

I more meant a better use of the resources we have -- some of which could be used for space development.

I also don't think space development takes huge resources. It takes huge specialization. Which in our system is huge money. But I think that would change with time. If only because the technologies would mature and the manufacturing challenges would be easier to solve.

================As far as extra-terrestrial resources, I expect they would only be utilized by extra-terrestrial activities. And it would be a long way off.

If you have a Mars Base for scientific study .. it would be nice if they can begin to acquire some of their resources locally.

"The cake story was about M. Antoinette supposedly being so clueless she didn't know the masses didn't have cake."

You're absolutely correct. The masses don't have cake, and nobody could wish it into existence. But it turned out that revolutionary reorganization didn't solve the fundamental problems that were causing a lack of bread in the cities. So the French wound up stealing it from somebody else -- and their cake too.

"As far as the utilization of resources goes -- we won't know that until they start utilizing them, will we?

Right now we steal resources from other countries for numbers on a ledger.

So not only aren't they using their resources for their own betterment - they are sending goods to us - for nothing."

Really? The Saudis, Kuwaitis, etc. aren't getting paid for their oil? I've been to the Middle East, Phil. I can guarantee you that they aren't giving it up for nothing. Or maybe you're talking about minerals from Africa and South America? They're getting paid too, even if they give kickbacks and don't evenly distribute the wealth. Even in the days of European colonialism, the "stolen" resources were paid for with armies, colonial administrations, and the loss of a lot of human capital to tropical diseases. TANSTAAFL.

I'm not sure what other resources you think aren't being utilized. Care to enumerate?

"Interesting example -- didn't the Athenians discover some silver which they used to build up their Navy prior to the big invasion at Thermopylae?

Other than its value as currency what is silver used for when making War Galleys?

Basically they were able to "pay" people to build the galleys and for the raw materials.

If they had had a fiat currency it might have amounted to the same thing. They would have paid for the people and materials and the boats would have been built.

After all there was very little real need for the silver."

A couple of problems with your theory here:

1. Silver is commodity money, not fiat money. It cost effort to extract and refine, giving it real value to those it was offered to in exchange.

2. Inflating a fiat money supply is the functional equivalent of taxation -- on credit. The government buys at full value, but as the economy adjusts to the new balance of money vs resources, the money injected into the economy buys less than full time-of-issue value. What the government is actually doing is concentrating a resource allocation in time at the moment of issue. But the cost to the economy is lowered allocations later on, because the money buys less at that time.

Actually, it turns out that no, you don't just create fiat money out of thin air. It's value is defined by the strength of the economy in which it is legal tender. You can issue however many units of your fiat money you want, but each unit is only worth what it can buy in the market. If you issue ten units of money per unit of resources available in the market, your money is worth less per unit than if you had issued only five.

The reason that the Saudis, Kuwaitis, et al accept US dollars as real money payment is that the US economy is so strong that they don't have to trade directly with the US to recapture value. They can trade with anybody that accepts dollars -- which is essentially anybody at all. Now, it's all based on the theory that the US dollar can be returned to the US eventually for US goods, but no given dollar has to be. As long as the US is perceived to be economically strong, just the ability to go there for exchange is enough, whether one actually does so or not.

"In the silver example - the fact it took labor to mine the silver actually strengthens my point. They not only had enough labor to mine the silver but also to build all the boats."

IIRC, the Athenians used slave labor to mine the silver and probably a large number of slaves to build the ships. That labor -- both free and slave -- was diverted from other projects. It hadn't been previously idle. It took a lot of convincing on the part of the naval party to convince Athens to invest in a navy, not because there was a debate about what to do with unused labor, but a debate about what to do with the windfall silver discovery. Themistocles wanted to buy ships, while Aristides wanted to distribute it among the citizens (kind of a "stimulus package" if you will). It should be remembered that the pressure of Persian expansionism heavily influenced the decision as well. In any case, the navy did not arise out of unused manpower, but a windfall discovery of new commodity resources that could be exchanged for a navy.

"All for a 'commodity' that's only real value was as a currency (primarily at that time)"

Silver was used for utensils, storage containers, jewelry, decorative items, and even medicine. It's high value derived from its rarity compared to its perceived utility. It could be used as money because it was directly convertible into useful -- or at least highly desired -- items. (One of the big problems with deasing of coinage, along with the reduction in the precious metal contained in each coin was the, was that it changed the metalurgical properties of the money supply, making it harder to use as something other than money.)

It's getting something for tokens which in turn can be exchanged for value on demand. Those tokens are only nothing if they aren't backed by an economy that can remunerate their value. And if they're not reliably backed, those tokens wouldn't be accepted in the first place.

"As for the silver - the vast majority/all of the non-coin uses were as Luxury items. Which is not a resource needed for building ships."

Vast majority? The Pheonecians and Egyptians regularly used silver for food and beverage storage because it has preservative effects. Hardly a luxury usage, even if limited to the relatively affluent.

In any case, silver had a real, not fiat value. Nobody said, let's make silver money because we say so. The market had to accept that silver was money, and just as valuable as anything else they might have exchanged goods and services for. If that value derived from luxury application rather than utility as a cow manure shovel is irrelevant.

IIRC, the Athenians used slave labor to mine the silver and probably a large number of slaves to build the ships. That labor -- both free and slave -- was diverted from other projects. It hadn't been previously idle. It took a lot of convincing on the part of the naval party to convince Athens to invest in a navy, not because there was a debate about what to do with unused labor, but a debate about what to do with the windfall silver discovery. Themistocles wanted to buy ships, while Aristides wanted to distribute it among the citizens (kind of a "stimulus package" if you will). It should be remembered that the pressure of Persian expansionism heavily influenced the decision as well. In any case, the navy did not arise out of unused manpower, but a windfall discovery of new commodity resources that could be exchanged for a navy.

Which pretty much sums up how resources are allocated; based on what is seen and desired as the most useful (highest ROI) means of using the resources. Had there been no Persian threat on the horizon, the idea of diverting manpower and resources towards shipbuilding would have had far less support, regardless of what sort of currency existed.

The United States faces a similar issue during the Civil War. Government spending had so far outstripped revenues and backing that "Greenbacks" were issued to fill the void. Since the concept of paper money did not exist in ancient Greece, it is hard to say what the Athenians could have done faced with a Persian threat but no silver mines, but they would have thought of something. After all, during the Peloponnesian wars, Athens did lose their fleet, the flower of their army and most of their trade partners/subjects after the disaster at Sicily and still managed to fight on against Sparta and her Allies (backed by Persian funds) for almost a decade more.